scons_gd/scons/doc/user/parseflags.xml

<?xml version='1.0'?>
<!DOCTYPE sconsdoc [
    <!ENTITY % scons SYSTEM "../scons.mod">
    %scons;

    <!ENTITY % builders-mod SYSTEM "../generated/builders.mod">
    %builders-mod;
    <!ENTITY % functions-mod SYSTEM "../generated/functions.mod">
    %functions-mod;
    <!ENTITY % tools-mod SYSTEM "../generated/tools.mod">
    %tools-mod;
    <!ENTITY % variables-mod SYSTEM "../generated/variables.mod">
    %variables-mod;
]>

<section id="sect-parseflags"
         xmlns="http://www.scons.org/dbxsd/v1.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://www.scons.org/dbxsd/v1.0 http://www.scons.org/dbxsd/v1.0/scons.xsd">
<title>Separating Compile Arguments into their Variables: the &ParseFlags; Function</title>

<!--

  MIT License

  Copyright The SCons Foundation

  Permission is hereby granted, free of charge, to any person obtaining
  a copy of this software and associated documentation files (the
  "Software"), to deal in the Software without restriction, including
  without limitation the rights to use, copy, modify, merge, publish,
  distribute, sublicense, and/or sell copies of the Software, and to
  permit persons to whom the Software is furnished to do so, subject to
  the following conditions:

  The above copyright notice and this permission notice shall be included
  in all copies or substantial portions of the Software.

  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY
  KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE
  WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

-->

 <para>

 &SCons; has a bewildering array of &consvars;
 for different types of options when building programs.
 Sometimes you may not know exactly which variable
 should be used for a particular option.

 </para>

 <para>

 &SCons; &consenvs; have a &f-link-ParseFlags; method
 that takes a set of typical command-line options
 and distributes them into the appropriate &consvars;
 Historically, it was created to support the &f-link-ParseConfig; method,
 so it focuses on options used by the GNU Compiler Collection (GCC)
 for the C and C++ toolchains.

 </para>

 <para>

 &ParseFlags; returns a dictionary containing the options
 distributed into their respective &consvars;.
 Normally, this dictionary would then be passed to &f-link-MergeFlags;
 to merge the options into a &consenv;,
 but the dictionary can be edited if desired to provide
 additional functionality.
 (Note that if the flags are not going to be edited,
 calling &MergeFlags; with the options directly
 will avoid an additional step.)

 </para>

 <scons_example name="parseflags_ex1">
   <file name="SConstruct" printme="1">
env = Environment()
d = env.ParseFlags("-I/opt/include -L/opt/lib -lfoo")
for k, v in sorted(d.items()):
    if v:
        print(k, v)
env.MergeFlags(d)
env.Program("f1.c")
   </file>
   <file name="f1.c">
int main() { return 0; }
   </file>
 </scons_example>

 <scons_output example="parseflags_ex1" os="posix" suffix="1">
    <scons_output_command>scons -Q</scons_output_command>
 </scons_output>

 <para>

 Note that if the options are limited to generic types
 like those above,
 they will be correctly translated for other platform types:

 </para>

 <scons_output example="parseflags_ex1" os="win32" suffix="2">
    <scons_output_command>scons -Q</scons_output_command>
 </scons_output>

 <para>

 Since the assumption is that the flags are used for the GCC toolchain,
 unrecognized flags are placed in &cv-link-CCFLAGS;
 so they will be used for both C and C++ compiles:

 </para>

 <scons_example name="parseflags_ex2">
   <file name="SConstruct" printme="1">
env = Environment()
d = env.ParseFlags("-whatever")
for k, v in sorted(d.items()):
    if v:
        print(k, v)
env.MergeFlags(d)
env.Program("f1.c")
   </file>
   <file name="f1.c">
void main() { return 0; }
   </file>
 </scons_example>

 <scons_output example="parseflags_ex2" suffix="1">
    <scons_output_command>scons -Q</scons_output_command>
 </scons_output>

 <para>

 &ParseFlags; will also accept a (recursive) list of strings as input;
 the list is flattened before the strings are processed:

 </para>

 <scons_example name="parseflags_ex3">
   <file name="SConstruct" printme="1">
env = Environment()
d = env.ParseFlags(["-I/opt/include", ["-L/opt/lib", "-lfoo"]])
for k, v in sorted(d.items()):
    if v:
        print(k, v)
env.MergeFlags(d)
env.Program("f1.c")
   </file>
   <file name="f1.c">
void main() { return 0; }
   </file>
 </scons_example>

 <scons_output example="parseflags_ex3" suffix="1">
    <scons_output_command>scons -Q</scons_output_command>
 </scons_output>

 <para>

 If a string begins with a an exclamation mark (<literal>!</literal>),
 the string is passed to the shell for execution.
 The output of the command is then parsed:

 </para>

 <scons_example name="parseflags_ex4">
   <file name="SConstruct" printme="1">
env = Environment()
d = env.ParseFlags(["!echo -I/opt/include", "!echo -L/opt/lib", "-lfoo"])
for k, v in sorted(d.items()):
    if v:
        print(k, v)
env.MergeFlags(d)
env.Program("f1.c")
   </file>
   <file name="f1.c">
void main() { return 0; }
   </file>
 </scons_example>

 <scons_output example="parseflags_ex4" suffix="1">
    <scons_output_command>scons -Q</scons_output_command>
 </scons_output>

 <para>

 &ParseFlags; is regularly updated for new options;
 consult the man page for details about those currently recognized.

 </para>

</section>