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Pragmas

Pragmas are a method for providing additional information to genom, beyond what is conveyed in the language itself. They are introduced by the #pragma directive, followed by arguments. genom understands the following pragmas:

#pragma requires

#pragma requires is recognized by 'both' genom-pcpp preprocessor and 'genom3'. It indicates an external dependency on a software package that is required to parse the current specification. #pragma requires assumes that the package is using the pkg-config utility (see http://www.freedesktop.org/wiki/Software/pkg-config) and a .pc file is available. This has the same effect as placing requires directives in all components (Component declaration) but saves the need to pass -I and -D directives to genom3 (see General options) as they are automatically computed.

The pragma syntax is as follow:

#pragma requires " 'package' [ >= 'version' ]"

#pragma requires accepts a string argument in the form package [>= version]. genom-pcpp interprets it by running pkg-config --cflags on the string argument. It then adds the resulting -I and -D flags as if they had been passed on the command line. Note that the flags are added 'at the current processing location', so they do not influence already preprocessed input. The pkg-config utility is found in PATH, or via the PKG_CONFIG environment variable if defined (see Environment variables).

The pragma argument is added to the require property of all components later defined in a specification.

#pragma provides

#pragma provides achieves the same effect as if 'all' components of a specification defined the same provides property (see Component declaration). This directive is mostly useful for templates implementation, so that they can provide a common interface to all user defined components.

The pragma syntax is as follow:

#pragma provides 'interface'

#pragma masquerade

This directive applies to an IDL type definition in a component interface. It is meant for aliasing the IDL type description to a native object that cannot be described in IDL. The exact nature of the native object depends on the template used for code generation, so it is only described as a raw string here and not interpreted by genom.

The pragma syntax is as follow:

#pragma masquerade 'template' 'type' 'data…​'

The 'template' argument is a free form string that indicates to which template the directives applies. Templates can lookup this name and take the appropriate actions based on this information. 'type' is the name of the IDL type thas is to be masqueraded. 'data' describes how the masquerading will be done, and is template specific. Refer to the documentation of the template you are using for a precise description of the syntax and semantics of 'data'.