#Cmdline
Preprocessor directive
Syntax
`
#cmdline "args..."
`
Parameters
`args...`
argument list (separated by spaces) of valid `Compiler Options` except `-print` and also generic option `-help`.
Description
`#cmdline` is a pre-processor directive that allows specifying `compiler options` from inside the first specified fb source file. The first source file is the first specified '.bas' file given on the shell or IDE command line invoking the fbc compiler. `#cmdline` directives specified in the first source file affect all source files subsequently compiled. `#cmdline` directives inside source files other than the first source file are ignored.
`#cmdline` is only allowed at module scope and can be conditionally processed with `#if` pre-processor statements. `#cmdline` statements must appear before any declarative or executable statements. Any `#cmdline` statements after the first declarative or executable statement are ignored.
`#cmdline` directives are processed on the first pass of the the first '.bas' source file when they appear in the source file. If an invalid command line option is given in the `#cmdline` statment, compilation immediately aborts. `#cmdline` directives are ignored on the second pass of the source file even if a conditional `#if` would add something different on the second pass.
At first fbc initializes as usual and begins parsing the fb source code using the options given from the shell or IDE's `fbc ...` command line. As `#cmdline` directives are processed, they are merged into the current compiler configuration. Depending on the command line options encountered, fbc can continue parsing, restart the parser, or restart fbc (for example: no restart after `#cmdline "-mt"`, restart the parser after `#cmdline "-gen gcc"`, restart the build after `#cmdline "-target win64"`).
fbc has no clever way to detect when all the `#cmdline` directives in source have been processed, so there are 2 pseudo command line options to instruct fbc what to next if it is necessary:
`#cmdline "-end"`
option to restart parser or build if needed.
`#cmdline "-restart"`
option to always restart build.
If neither `#cmdline "-end"` nor `#cmdline "-restart"` were encountered, fbc continues processing to the end of the first source file and restarts only if necessary.
Adding `-z nocmdline` in the shell/IDE command line option ignores `#cmdline` directives completely in source and allows user to override all source directives using the shell/IDE `fbc` compiler command line only.
Adding `-w all` on the shell/IDE command line option allows to get warnings about ignored `#cmdline` directives.
Example
Add a simple option in source to set the optimization level for GCC:
`
#cmdline "-O 2"
Print __FB_OPTIMIZE__ '' just to check the optimization level
Sleep
`
When #cmdline is not processed (no 'invalid command-line option' error message is reported):
(fbc parser is active when checking for #cmdline, so it's expected that it follows sames rules as any other source code)
`
'' not processed in single line comments
'#cmdline "asdf"
'' not processed in multi line comments
/'
#cmdline "-asdf"
'/
'' not processed in strings
Print "#cmdline ""-asdf"""
'' not processed if skipping over a conditional
#if 0
#cmdline "-asdf"
#endif
'' not processed when defining macros (as long as the macro is not called)
#macro DOARGS
#cmdline "-asdf"
#endmacro
Sleep
`
Set options in source based on real `fbc ...` compiler command line option given:
(full error checking is activated depending if debug option '-g' was given on the `fbc ...` compiler command line)
`
'' '-g' command line option given on the real ##//fbc ...//## compiler command line?
#if __FB_DEBUG__
#cmdline "-exx -w pedantic -w constness"
#endif
`
Define a global symbol for all modules, starting with two modules: main.bas and tools.bas, and compile both with the single '$ fbc main.bas' compiler command line:
(this is different than #include tools.bas in main.bas because the two modules are compiled separately then linked)
`
'' main.bas
''
'' compile with:
'' $ fbc main.bas
''
'' and will be same as if we did:
'' $ fbc main.bas tools.bas -d DoTrickyStuff
'' add the tools module
#cmdline "-b tools.bas" '' or: #cmdline "tools.bas"
'' gobal #define for all modules
#cmdline "-d DoTrickyStuff"
Declare Function IsTrickyTools() As Boolean
#ifdef DoTrickyStuff
Print "DoTrickyStuff is defined in the main.bas module"
#endif
If IsTrickyTools() Then
Print "DoTrickyStuff is defined in the tools.bas module"
End If
Sleep
`
`
'' tools.bas
''
Function IsTrickyTools() As Boolean
#ifdef DoTrickyStuff
Return True
#else
Return False
#endif
End Function
`
Version

- Since fbc 1.09.0

Differences from QB

- New to FreeBASIC

See also

- fbc command-line
- Compiler Options
- Intrinsic Defines