The build system analyses the directory tree containing a set of source code, processes the configuration, and invokes make to compile/build the source code into the project executables. In this chapter, we shall use many examples to explain how to use the build system. At the end of this chapter, you should be able to use the build system, either by defining the build configuration file directly or by using the extract system to generate a suitable build configuration file.
To invoke the build system, simply issue the command:
fcm build
By default, the build system searches for a build configuration file "bld.cfg" in "$PWD" and then "$PWD/cfg". If a build configuration file is not found in these directories, the command fails with an error. If a build configuration file is found, the system will use the configuration specified in the file to perform the build. If you use the extract system to extract your source tree, a build configuration should be written for you automatically at the "cfg/" sub-directory of the destination root directory.
If the root directory of the build does not exist, the system performs a new full build at this directory. If a previous build already exists at this directory, the system performs an incremental build. If a full (fresh) build is required for whatever reason, you can invoke the build system using the "-f" option, (i.e. the command becomes "fcm build -f").
The build system uses GNU make to perform the majority of the build. GNU make has a "-j <jobs>" option to specify the number of <jobs> to run simultaneously. Invoking the build system with the same option triggers this option when the build system invokes the make command. The argument to the option <jobs> must be an integer. The default is 1. For example, the command "fcm build -j 4" will allow make to perform 4 jobs simultaneously.
For further information on the build command, please see FCM Command Reference > fcm build.
The build configuration file is the user interface of the build system. It is a line based text file. You can create your own build configuration file or you can use the extract system to create one for you. For a complete set of build configuration file declarations, please refer to the Annex: Declarations in FCM build configuration file.
Suppose we have a directory at "$HOME/example". Its sub-directory at "$HOME/example/src" contains a source tree to be built. You may want to have a build configuration file "$HOME/example/cfg/bld.cfg", which may contain:
| Build configuration example 1 - basic build configuration |
|---|
cfg::type bld # line 1 cfg::version 1.0 # line 2 dir::root $HOME/example # line 4 target foo.exe bar.exe # line 6 tool::fc ifc # line 8 tool::fflags -O3 # line 9 tool::cc gcc # line 10 tool::cflags -O3 # line 11 tool::ld ifc # line 12 tool::ldflags -O3 -L$(HOME)/lib -legg -lham # line 13 |
Here is an explanation of what each line does:
When we invoke the build system, it reads the above configuration file. It will go through various internal processes, such as dependency generations, to obtain the required information to prepare the Makefile of the build. (All of which will be described in later sections.) The Makefile of the build will be placed at "$HOME/example/bld". The system will then invoke make to build the targets specified in line 6, i.e. "foo.exe" and "bar.exe" using the build tools specified between line 8 to line 13. On a successful build, the target executables will be sent to "$HOME/example/bin/". The build system also creates a shell script called "fcm_env.ksh" in "$HOME/example/". If you source the shell script, it will export your PATH environment variable to search the "$HOME/example/bin/" directory for executables.
N.B. You may have noticed that the "-c" (compile to object file only) option is missing from the compiler flags declarations. This is because the option is inserted automatically by the build system, unless it is already declared.
| Note - declaration of source directories for build |
|---|
Source directories do not have to reside in the source sub-directory
of the build root directory. They can be anywhere, but you will have to
declare them individually, using the label SRC::<pcks>, where
<pcks> is the sub-package name in which the source directory
belongs. E.g.
# Declare a source directory in the sub-package "foo::bar" src::foo::bar $HOME/foo/bar By default, the build system searches the "src/" sub-directory of the build root directory for sub-package source directories. If all source directories are already declared explicitly, you can switch off the automatic directory search by setting the SEARCH_SRC flag to 0. E.g. search_src 0 As mentioned in the previous chapter, the name of a sub-package <pcks> provides a unique namespace for a file container. The name of a sub-package is a list of words delimited by the double colons "::", which is turned into the double underscores "__" by the build system internally. Please avoid using "::" and "__" for naming your files and directories. In the build system, the sub-package name also provides an "inheritance" relationship for sub-packages. For instance, we may have a sub-package called "foo::bar::egg", which belongs to the sub-package "foo::bar", which belongs to the package "foo".
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As mentioned earlier, you can obtain a build configuration file through the extract system. The following example is what you may have in your extract configuration in order to obtain a similar configuration as example 1:
| Build configuration example 2 - created by the extract system |
|---|
cfg::type ext # line 1 cfg::version 1.0 # line 2 dest::rootdir $HOME/example # line 4 bld::target foo.exe bar.exe # line 6 bld::tool::fc ifc # line 8 bld::tool::fflags -O3 # line 9 bld::tool::cc gcc # line 10 bld::tool::cflags -O3 # line 11 bld::tool::ld ifc # line 12 bld::tool::ldflags -O3 -L$(HOME)/lib -legg -lham # line 13 # ... and other declarations for repositories and source directories ... |
It is easy to note the similarities and differences between example 1 and example 2. Example 2 is an extract configuration file. It extracts to a destination root directory that will become the root directory of the build. Line 6 to line 13 are the same declarations, except that they are now prefixed with "BLD::". In an extract configuration file, any lines prefixed with "BLD::" means that they are build configuration setting. These lines are "ignored" by the extract system but are parsed down to the output build configuration file, with the "BLD::" prefix removed. (Note: the "BLD::" prefix is optional for declarations in a build configuration file.)
N.B. If you use the extract system to mirror an extraction to a remote machine, the extract system will assume that the root directory of the remote destination is the root directory of the build, and that the build will be carried out in the remote machine.
If a source file called "foo.f90" contains a main program, the default behaviour of the system is to name its executable "foo.exe". The root name of the executable is the same as the original file name, but its file extension is replaced with ".exe". The output extension can be altered by re-registering the extension for output EXE files. How this can be done will be discussed later in the sub-section File Type.
If you need to alter the full name of the executable, you can use the "EXE_NAME::" declaration. For example, the declaration:
bld::exe_name::foo bar
will rename the executable of "foo.f90" from "foo.exe" to "bar".
Note: the declaration label is "bld::exe_name::foo" (not "bld::exe_name::foo.exe") and the executable will be named "bar" (not "bar.exe").
Another way to alter the full name of the executable is to use the package configuration file, which will be discussed later in the sub-section Using a package configuration file.
As discussed in the first example, the compiler commands and their flags can be set via the "TOOL::" declarations. A simple "TOOL::FFLAGS" declaration, for example, alters the compiler options for compiling all Fortran source files in the build. If you need to alter the compiler options only for the source files in a particular sub-package, it is possible to do so by adding the sub-package name to the declaration label. For example, the declaration label "TOOL::FFLAGS::ops::code::OpsMod_Control" will ensure that the declaration only applies to the code in the sub-package "ops::code::OpsMod_Control". You can even make declarations down to the individual source file level. For example, the declaration label "TOOL::FFLAGS::ops::code::OpsMod_Control::Ops_Switch" will ensure that the declaration applies only for the file "Ops_Switch.f90".
N.B. Although the prefix "TOOL::" and the tool names are case-insensitive, sub-package names are case sensitive in the declarations. Internally, tool names are turned into uppercase, and the sub-package delimiters are changed from the double colons "::" to the double underscores "__". When the system generates the Makefile for the build, each "TOOL" declaration will be exported as an environment variable. For example, the declaration "tool::fflags::ops::code::OpsMod_Control" will be exported as "FFLAGS__ops__code__OpsMod_Control".
N.B. Although you can declare different compiler flags, linker commands and linker flags for different sub-packages, you cannot declare different compilers for different sub-packages.
The following is an example setting in an extract configuration file based on example 2:
| Build configuration example 3 - compiler flags for different sub-packages |
|---|
cfg::type ext cfg::version 1.0 dest::rootdir $HOME/example bld::target foo.exe bar.exe bld::tool::fc ifc bld::tool::fflags -O3 # line 9 bld::tool::cc gcc bld::tool::cflags -O3 bld::tool::ld ifc bld::tool::ldflags -L$(HOME)/lib -legg -lham bld::tool::fflags::ops -O1 -C # line 15 bld::tool::fflags::gen -O2 # line 16 # ... and other declarations for repositories and source directories ... |
In the example above, line 15 alters the Fortran compiler flags for "ops", so that all source files in "ops" will be compiled with optimisation level 1 and will have runtime error checking switched on. Line 16, alters the Fortran compiler flags for "gen", so that all source files in "gen" will be compiled with optimisation level 2. All other Fortran source files will use the global setting declared at line 9, so they they will all be compiled with optimisation level 3.
| Note - changing compiler flags in incremental builds |
|---|
Suppose you have performed a successful build using the configuration
in example 3, and you have decided to change some of the compiler
flags, you can do so by altering the appropriate flags in the build
configuration file. When you trigger an incremental build, the system
will detect changes in compiler flags automatically, and update only
the required targets. The following hierarchy is followed:
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N.B. For a full list of build tools declarations, please see Annex: Declarations in FCM build configuration file > list of tools.
For each Fortran 9X source file containing standalone subroutines and/or functions, the system generates an interface file and sends it to the "inc/" sub-directory of the build root. An interface file contains the interface blocks for the subroutines and functions in the original source file. In an incremental build, if you have modified a Fortran 9X source file, its interface file will only be re-generated if the content of the interface has changed.
Consider a source file "foo.f90" containing a subroutine called "foo". In a normal operation, the system writes the interface file to "foo.interface" in the "inc/" sub-directory of the build root. By default, the root name of the interface file is the same as that of the source file, and is case sensitive. You can change this behaviour using a "TOOL::INTERFACE" declaration. E.g.:
bld::tool::interface program # The default is "file"
In such case, the root name of the interface file will be named in lower case after the first program unit in the file.
The default extension for an interface file is ".interface". This can be modified through the input and output file type register, which will be discussed in a later section on File Type.
In most cases, we modify procedures without altering their calling interfaces. Consider another source file "bar.f90" containing a subroutine "bar". If "bar" calls "foo", it is good practice for "bar" to have an explicit interface for "foo". This can be achieved if the subroutine "bar" has the following within its declaration section:
INCLUDE 'foo.interface'
The source file "bar.f90" is now dependent on the interface file "foo.interface". This can make incremental build very efficient, as changes in the "foo.f90" file will not normally trigger the re-compilation of "bar.f90", provided that the interface of the subroutine "foo" remains unchanged. (However, the system is clever enough to know that it needs to re-link any executables that are dependent on the object file for the subroutine "bar".)
The default interface block generator is a piece of "plugged-in" Perl code originally developed by the ECMWF. It has been modified at the Met Office to work with FCM. Currently, the system can also work with the interface generator f90aib, which is a freeware obtained from Fortran 90 texts and programs, assembled by Michel Olagnon at the French Research Institute for Exploitation of the Sea. To do so, you need to make a declaration in the build configuration file using the label "TOOL::GENINTERFACE". As for any other TOOL declarations, you can attach a sub-package name to the label. The change will then apply only to source files within that sub-package. If "TOOL::GENINTERFACE" is declared to have the value "NONE", interface generation will be switched off. The following are some examples:
| Build configuration example 4 - Fortran 9X interface block generator |
|---|
# This is an EXTRACT configuration file ... # ... some other declarations ... bld::tool::geninterface f90aib # line 5 bld::tool::geninterface::foo ECMWF # line 6 bld::tool::geninterface::bar none # line 7 # ... some other declarations ... |
In line 5, the global interface generator is now set to f90aib. In line 6, the interface generator for the package "foo" is set to the ECMWF one. In line 7, by setting the interface generator for the package "bar" to the "none" keyword, no interface file will be generated for source files under the package "bar".
Switching off the interface block generator can be useful in many circumstances. For example, if the interface block is already provided manually within the source tree, or if the interface block is never used by other program units, it is worth switching off the interface generator for the source file to speed up the build process.
The build system has a built-in dependency scanner, which works out the dependency relationship between source files, so that they can be built in the correct order. The system scans all source files of known types for all supported dependency patterns. Dependencies of source files in a sub-package are written in a cache, which can be retrieved for incremental builds. (In an incremental build, only changed source files need to be re-scanned for dependency information. Dependency information for other files are retrieved from the cache.) The dependency information is parsed to the make rule generator, which writes the Makefile fragment for building the source files in the sub-package. In an incremental build, a Makefile fragment for a sub-package is only re-generated if a source file in the sub-package has changed.
The make rule generator generates different make rules for different dependency types. The following dependency patterns are automatically detected by the current system:
If you want your code to be built automatically by the FCM build system, you should also design your code to conform to the following rules:
| Note - setting build targets |
|---|
|
The Makefile (and its include fragments) generated by the
build system contains a list of targets that can be built. The build
system allows you to build (or perform the actions of) any targets that
are present in the generated Makefile. There are two ways to
specify the targets to be built. Firstly, you can use the TARGET
declarations in your build configuration file to specify the default
targets to be built. These targets will be set as dependencies of the
"all" target in the generated Makefile, which is the default
target to be built when make is invoked by FCM. Alternatively,
you can use the "-t" option when you invoke the "fcm build" command. The
option takes an argument, which should be a colon ":" separated list of
targets to be built. When the "-t" option is set, FCM invokes
make to build these targets instead. (E.g. if we invoke the
build system with the command "fcm build -t foo.exe:bar.exe", it will
invoke make to build "foo.exe" and "bar.exe".)
If you do not specify any explicit targets, the system will search your source tree for main programs:
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Apart from the usual dependency patterns described in the previous sub-section, the automatic dependency scanner also recognises two special directives when they are inserted into a source file:
There are situations when you need to bypass the automatic dependency scanner. In such case, you may need to use a package configuration file. For further information, please refer to the sub-section on Using a package configuration file.
Another way to specify external dependency is to use the EXE_DEP declaration to declare extra dependencies. The declaration normally applies to all main programs, but if the the form EXE_DEP::<target> is used, it will only apply to <target>, (which must be the name of a main program target). If the declaration is made without a value, the main programs will be set to depend on all object files. Otherwise, the value can be supplied as a space delimited list of items. Each item can be either the name of a sub-package or an object target. For the former, the main programs will be set to depend on all object files within the sub-package. For the latter, the main programs will be set to depend on the object target. The following are some examples:
| Build configuration example 5 - extra executable dependency |
|---|
cfg::type ext cfg::version 1.0 bld::exe_dep::foo.exe foo::bar egg.o # line 4 bld::exe_dep # line 5 # ... some other declarations ... |
Here is an explanation of what each line does:
| Note - naming of object files |
|---|
| By default, object files are named with the suffix ".o". For a
Fortran source file, the build system uses the lower case name of the
first program unit within the file to name its object file. For example,
if the first program unit in the Fortran source file "foo.f90" is
"PROGRAM Bar", the object file will be "bar.o". For a C source file, the
build system uses the lower case root name of the source file to name
its object file. For example, a C source file called "egg.c" will have
its object file named "egg.o".
The reason for using lower case to name the object files is because Fortran is a case insensitive language. Its symbols can either be in lower or upper case. E.g. the SUBROUTINE "Foo" is the same as the SUBROUTINE "foo". It can be rather confusing if the subroutines are stored in different files. When they are compiled and archived into a library, there will be a clash of namespace, as the Fortran compiler thinks they are the same. However, this type of error does not normally get reported. If "Foo" and "foo" are very different code, the user may end up using the wrong subroutine, which may lead to a very long debugging session. By naming all object files in lower case, this type of situation can be avoided. If there is a clash in names due to the use of upper/lower cases, it will be reported as warnings by make, (as "duplicated targets" for building "foo.o"). |
It is realised that there are situations when an automatically detected dependency should not be written into the Makefile. For example, the dependency may be a standard module provided by the Fortran compiler, and does not need to be built in the usual way. In such case, we need to have a way to exclude this module during an automatic dependency scan.
The EXCL_DEP declaration can be used to do just that. The following extract configuration contains some examples of the basic usage of the EXCL_DEP declaration:
| Build configuration example 6 - exclude dependency |
|---|
cfg::type ext cfg::version 1.0 bld::excl_dep USE::YourFortranMod # line 4 bld::excl_dep INTERFACE::HerFortran.interface # line 5 bld::excl_dep INC::HisFortranInc.inc # line 6 bld::excl_dep H::TheirHeader.h # line 7 bld::excl_dep OBJ::ItsObject.o # line 8 # ... some other declarations ... |
Here is an explanation of what each line does:
An EXCL_DEP declaration normally applies to all files in the build. However, you can suffix it with the name of a sub-package, i.e. EXCL_DEP::<pcks>. In such case, the declaration will only apply while scanning for dependencies in the source files in the sub-package named <pcks>.
You can also exclude all dependency scan of a particular type. To do so, simply declare the type in the value. For example, if you do not want the build system to scan for the [CALLS: <executable>] directive in the comment lines of your scripts, you can make the following declaration:
bld::excl_dep EXE
N.B. Currently, the build system is unable to detect changes in EXCL_DEP declarations. Therefore, you will need to invoke the build system in full build mode if you have changed these settings.
If it is required to link Fortran executables with BLOCKDATA program units, you must declare the executable targets and the objects containing the BLOCKDATA program units using the BLOCKDATA::<target> declarations. For example, if "foo.exe" is an executable target depending on the objects of the BLOCKDATA program units "blkdata.o" and "fbk.o", you will make the following declarations:
bld::blockdata::foo.exe blkdata fbk
If all your executables are dependent on "blkdata.o" and "fbk.o", you will make the following declarations:
bld::blockdata blkdata fbk
If you are interested in building library archives, the build system allows you to do it in a relatively simple way. For each sub-package in the source tree, there is a target to build a library containing all the objects compiled from the source files (that are not main programs) within the sub-package. If the sub-package contains children sub-packages, the object files of the children will also be included recursively. By default, the library archive is named after the sub-package, in the format "lib<pcks>.a". (For example, the library archive for the package "foo::bar::egg" will be named "libfoo__bar__egg.a" by default.) If you do not like the default name for the sub-package library, you can use the LIB::<pcks> declaration to rename it, as long as the new name does not clash with other targets. For example, to rename "libfoo__bar__egg.a" to "libham.a", you will make the following declaration in your extract configuration file:
bld::lib::foo::bar::egg ham
In addition to sub-package libraries, you can also build a global library archive for the whole source tree. By default, the library is named "libfcm_default.a", but you can rename it using the LIB declaration as above. For example, to rename the library to "libmy-lib.a", you will make the following declaration in your extract configuration file:
bld::lib my-lib
When a library archive is created successfully, the build system will automatically generate the relevant exclude dependency configurations in the "etc/" sub-directory of the build root. You will be able to include these configurations in subsequent builds that utilise the library. The root names of the configuration files match those of the library archives that you can create in the current build, but the extension "*.a" is replaced with "*.cfg". For example, the exclude dependency configuration for "libmy-lib.a" is "libmy-lib.cfg".
As most modern compilers can handle pre-processing, the build system leaves pre-processing to the compiler by default. However, it is recognised that there are code written with pre-processor directives that can alter the argument list of procedures and/or their dependencies. If a source file requires pre-processing in such a way, we have to pre-process before running the interface block generator and the dependency scanner. The PP declaration can be used to switch on this pre-processing stage. The pre-processing stage can be switched on globally or for individual sub-packages only. The following is an example, using an extract configuration file:
| Build configuration example 7 - pre-processing switch |
|---|
cfg::type ext cfg::version 1.0 bld::pp::gen 1 # line 4 bld::pp::var::foo 1 # line 5 bld::tool::cppkeys GOOD WEATHER FORECAST # line 7 bld::tool::fppkeys FOO BAR EGG HAM # line 8 # ... some other declarations ... |
Here is an explanation of what each line does:
Source files requiring pre-processing may contain "#include" statements to include header files. For including a local file, its name should be embedded within a pair of quotes, i.e. 'file.h' or "file.h". If the header file is embedded within a pair of "<file.h>" angle brackets, the system will assume that the file can be found in a standard location.
The build system allows header files to be placed anywhere within the declared source tree. The system uses the dependency scanner, as described in the previous sub-section to scan for any header file dependencies. All source files requiring pre-processing and all header files are scanned. Header files that are required are copied to the "inc/" subdirectory of the build root, which is automatically added to the pre-processor search path via the "-I<dir>" option. The build system uses an internal logic similar to make to perform pre-processing. Header files are only copied to the "inc/" sub-directory if they are used in "#include" statements.
Unlike make, which only uses the timestamp to determine whether an item is out of date, the internal logic of the build system does this by inspecting the content of the file as well. In an incremental build, the pre-processed file is only updated if its content has changed. This avoids unnecessary updates (and hence unnecessary re-compilation) in an incremental build if the changed section of the code does not affect the output file.
Pre-processed code generated during the pre-processing stage are sent to the "ppsrc/" sub-directory of the build root. It will have a relative path that reflects the name of the declared sub-package. The pre-processed source file will have the same root name as the original source file. For C files, the same extension ".c" will be used. For Fortran files, the case of the extension will normally be dropped, e.g. from ".F90" to ".f90".
Following pre-processing, the system will use the pre-processed source file as if it is the original source file. The interface generator will generate the interface file using the pre-processed file, the dependency scanner will scan the pre-processed file for dependencies, and the compiler will compile the pre-processed source.
The TOOL::CPPKEYS and TOOL::FPPKEYS declarations are used to pre-define macros in the C and Fortran pre-processor respectively. This is implemented by the build system using the pre-processor "-D" option on each word in the list. The use of these declarations are not confined to the pre-process stage. If any source files requiring pre-processing are left to the compiler, the declarations will be used to set up the commands for compiling these source files.
The TOOL::CPPKEYS and TOOL::FPPKEYS declarations normally applies globally, but like any other TOOL declarations, they can be suffixed with sub-package names. In such cases, the declarations will apply only to the specified sub-packages.
| Note - changing pre-processor flags |
|---|
As for compiler flags, the build system detects changes in
pre-processor flags (TOOL::CPPFLAGS and TOOL::FPPFLAGS) and macro
definitions (TOOL::CPPKEYS and TOOL::FPPKEYS). If the pre-processor
flags or the macro definitions have changed in an incremental build,
the system will re-do all the necessary pre-processing. The following
hierarchy is followed:
|
The build system only knows what to do with an input source file if it knows what type of file it is. The type of a source file is normally determined automatically using one of the following three methods (in order):
In addition to the above, if a file is a Fortran or C source file, the system will attempt to open the source file to determine whether it contains a main program, module (Fortran only) or just standalone procedures. All these information will be used later by the build system to process the source file.
The build system registers a file type with a set of type flags delimited by the double colons "::". For example, a Fortran 9X source file is registered as "FORTRAN::FORTRAN9X::SOURCE". (Please note that the order of the type flags in the list is insignificant. For example, "FORTRAN::SOURCE" is the same as "SOURCE::FORTRAN".) For a list of all the type flags used by the build system, please see the input file extension type flags table in the Annex: Declarations in FCM build configuration file.
The following is a list of default input file extensions and their associated types:
| Extensions | Type flags | Description |
|---|---|---|
| .f .for .ftn .f77 | FORTRAN::SOURCE | Fortran 77 source file (assumed to be fixed format) |
| .f90 .f95 | FORTRAN::FORTRAN9X::SOURCE | Fortran 9X source file (assumed to be free format) |
| .F .FOR .FTN .F77 | FPP::SOURCE | Fortran 77 source file (assumed to be fixed format) that requires pre-processing |
| .F90 .F95 | FPP::FPP9X::SOURCE | Fortran 9X source file (assumed to be free format) that requires pre-processing |
| .c | C::SOURCE | C source file |
| .h .h90 | CPP::INCLUDE | Pre-processor "#include" header file |
| .o .obj | BINARY::OBJ | Compiled binary object |
| .exe | BINARY::EXE | Binary executable |
| .a | BINARY::LIB | Binary object library archive |
| .sh .ksh .bash .csh | SHELL::SCRIPT | Unix shell script |
| .pl .pm | PERL::SCRIPT | Perl script |
| .py | PYTHON::SCRIPT | Python script |
| .tcl | TCL::SCRIPT | Tcl/Tk script |
| .pro | PVWAVE::SCRIPT | PVWave program |
| .cfg | CFGFILE | FCM configuration file |
| .inc | FORTRAN::FORTRAN9X::INCLUDE | Fortran INCLUDE file |
| .interface | FORTRAN::FORTRAN9X::INCLUDE::INTERFACE | Fortran 9X INCLUDE interface block file |
N.B. The extension must be unique. For example, the system does not support the use of ".inc" files for both "#include" and Fortran "INCLUDE".
The following is a list of supported file name patterns and their associated types:
| Patterns | Type flags | Description |
|---|---|---|
| *Scr_* *Comp_* *IF_* *Suite_* *Interface_* | SHELL::SCRIPT | Unix shell script, GEN-based project naming conventions |
| *List_* | SHELL::SCRIPT::GENLIST | Unix shell script, GEN "list" file |
| *Sql_* | SCRIPT::SQL | SQL script, GEN-based project naming conventions |
The following is a list of supported "#!" line patterns and their associated types:
| Patterns | Type flags | Description |
|---|---|---|
| *sh* *ksh* *bash* *csh* | SHELL::SCRIPT | Unix shell script |
| *perl* | PERL::SCRIPT | Perl script |
| *python* | PYTHON::SCRIPT | Python script |
| *tclsh* *wish* | TCL::SCRIPT | Tcl/Tk script |
The build system allows you to add or modify the register for input file extensions and their associated type using the INFILE_EXT::<ext> declaration, where <ext> is a file name extension without the leading dot. For example, in an extract configuration file, you may have:
| Build configuration example 8 - add/modify input file extension types |
|---|
cfg::type ext cfg::version 1.0 bld::infile_ext::foo CPP::INCLUDE # line 4 bld::infile_ext::bar FORTRAN::FORTRAN9X::INCLUDE # line 5 # ... some other declarations ... |
Here is an explanation of what each line does:
The INFILE_EXT declarations deal with extensions of input files. There is also a OUTFILE_EXT::<type> declaration that deals with extensions of output files. The declaration is opposite that of INFILE_EXT. The file <type> is now declared with the label, and the extension is declared as the value. It is worth noting that OUTFILE_EXT declarations use very different syntax for <type>, and the declared extension must include the leading dot. For a list of output types used by the build system, please see the output file extension types table in the Annex: Declarations in FCM build configuration file. An example is given below:
| Build configuration example 9 - modify output file extensions |
|---|
cfg::type ext cfg::version 1.0 bld::outfile_ext::mk .rule # line 4 bld::outfile_ext::mod .MOD # line 5 bld::outfile_ext::interface .intfb # line 6 # ... some other declarations ... |
Here is an explanation of what each line does:
N.B. If you have made changes to the file type registers, whether it is for input files or output files, it is always worth re-building your code in full-build mode to avoid unexpected behaviour.
As you can perform incremental extractions against pre-extracted source code, you can perform incremental builds against pre-compiled builds. The very same USE statement can be used to declare a build, which the current build will depend on. The only difference is that the declared location must contain a valid build configuration file. In fact, if you use the extract system to obtain your build configuration file, any USE declarations in the extract configuration file will also be USE declarations in the output build configuration file.
By declaring a USE statement, the current build automatically inherits settings from the pre-compiled build. The following points are worth noting:
inherit::target 1
For example, if build "B" USEs build "A", and both of them have a sub-package called "basic::element". In build "A", the sub-package contains the source files "earth.f90", "wind.f90" and "water.f90". In build "B", the sub-package contains "earth.f90" and "fire.f90". When the system searches for source files, it will look for source files in "B" before "A". Therefore, the source file "earth.f90" in "B" will override that of "A", and the files used for the build will be "earth.f90" and "fire.f90" from "B" and "wind.f90" and "water.f90" from "A".
You can switch off inheritance of source directories using an INHERIT::SRC declaration. This declaration can be suffixed with the name of a sub-package. In such case, the declaration applies only to the inheritance of the sub-package. Otherwise, it applies to all source directories. For example:
# Switch off inheritance of source directories in the "gen" sub-package inherit::src::gen 0
As an example, suppose we have already performed an extract and build based on the configuration in example 2, we can set up an extract configuration file as follows:
| Build configuration example 10 - "USE" a pre-compiled build |
|---|
cfg::type ext cfg::version 1.0 use $HOME/example # line 4 dest::rootdir $HOME/example9 # line 6 bld::inherit::target 1 # line 8 bld::target ham.exe egg.exe # line 9 bld::tool::fflags -O2 -w # line 11 bld::tool::cflags -O2 # line 12 # ... and other declarations for repositories and source directories ... |
Here is an explanation of what each line does:
It is recognised that the build system needs to be able to work with code that is not designed to work with the automatic dependency scanner. There are various techniques which can be used to achieve this, some of which are already described. However, it should be noted that these techniques are simply designed to allow code to be successfully built. They will not necessarily result in a good environment for developing such code, since for example, dependencies need to be manually maintained by the developer.
The final technique is the package configuration file. The package configuration file is a special source file to inform the build system about any additional information of the source files in the package. It must be a file called "@PACKAGE.cfg" in a source directory. For a full list of available declarations in the package configuration file, please refer to the Annex: Declarations in FCM build package configuration file.
The following is an example of how a package configuration file can be used to provide additional information to the build system for a source file:
| Package configuration example 1 - dependency information for a source file |
|---|
type::MyFortranProg.f90 FORTRAN::FORTRAN9X::SOURCE::PROGRAM # line 1 scan::MyFortranProg.f90 0 # line 2 intname::MyFortranProg.f90 myprog # line 3 target::MyFortranProg.f90 hello_world # line 4 dep::MyFortranProg.f90 USE::YourFortranMod # line 6 dep::MyFortranProg.f90 INTERFACE::HerFortran.interface # line 7 dep::MyFortranProg.f90 INC::HisFortranInc.inc # line 8 dep::MyFortranProg.f90 H::TheirHeader.h # line 9 dep::MyFortranProg.f90 OBJ::ItsObject.o # line 10 # ... some other declarations ... |
Here is an explanation of what each line does:
While the usual targets to be built are the executables associated with source files containing main programs, libraries or scripts, the build system also allows you to build "data" files. All files with no registered type are considered to be "data" files. For each sub-package, there is an automatic target for copying all "data" files to the "etc/" sub-directory of the build root. The name of the target has the form "<pcks>.etc", where <pcks> is the name of the sub-package (with package names delimited by the double underscore "__"). For example, the target name for sub-package "foo::bar" is "foo__bar.etc". This target is particularly useful for copying, say, all namelists in a sub-package to the "etc/" sub-directory of the build root.
At the end of a successful build, if the "etc/" sub-directory is not empty, the "fcm_env.ksh" script will export the environment variable FCM_ETCDIR to point to the "etc/" sub-directory. You should be able to use this environment variable to locate your data files.
The amount of diagnostic messages generated by the build system is normally set to a level suitable for normal everyday operation. This is the default diagnostic verbose level 1. If you want a minimum amount of diagnostic messages, you should set the verbose level to 0. If you want more diagnostic messages, you can set the verbose level to 2 or 3. You can modify the verbose level in two ways. The first way is to set the environment variable FCM_VERBOSE to the desired verbose level. The second way is to invoke the build system with the "-v <level>" option. (If set, the command line option overrides the environment variable.)
The following is a list of diagnostic output at each verbose level:
| Verbose level | Possible output |
|---|---|
| 0 |
|
| 1 |
|
| 2 |
|
| 3 |
|
The FCM build process can be summarised in five stages. Here is a summary of what is done in each stage:
| Sub-directory | Contents | Note |
|---|---|---|
| .cache/ | <cache files> | used internally by FCM |
| bin/ | <executable binaries and scripts> | - |
| bld/ | Makefile and <Makefile include files> | - |
| cfg/ | bld.cfg | this directory is not changed by the build system |
| done/ | <dummy "done" files> | used internally by the Makefile generated by FCM |
| etc/ | <miscellaneous data files> | - |
| flags/ | <dummy "flags" files> | used internally by the Makefile generated by FCM |
| inc/ | <include files> | such as *.h, *.inc, *.interface and *.mod files |
| lib/ | <object library archives> | - |
| obj/ | <compiled object files> | - |
| ppsrc/ | <source directories with pre-processed files> | - |
| src/ | <source directories> | this directory is not changed by the build system |
| tmp/ | <temporary objects and binaries> | files generated by the compiler/linker may be left here |