# to generate header prior to XS compilation
perl -MDevel::CallChecker=callchecker0_h \
-e 'print callchecker0_h' > callchecker0.h
# in Perl part of module
use Devel::CallChecker;
/* in XS */
#include "callchecker0.h"
cv_get_call_checker(cv, &ckfun, &ckobj);
static OP *my_ckfun(pTHX_ OP *o, GV *namegv, SV *ckobj);
cv_set_call_checker(cv, my_ckfun, ckobj);
This module provides the implementation of the functions at runtime (on Perls where they are not provided by the core). It also, at compile time, supplies the C header file and link library which provide access to the functions. In normal use, ``callchecker0_h'' and ``callchecker_linkable'' should be called at build time (not authoring time) for the module that wishes to use the C functions.
Whether the subroutine is statically identifiable is determined in accordance with the prevailing standards of the Perl version being used. The same criteria are used that the core uses to determine whether to apply a prototype to a subroutine call. From version 5.11.2 onwards, the subroutine can be determined if the RV that the "rv2cv" is to operate on is provided by a suitable "gv" or "const" op. Prior to 5.11.2, only a "gv" op will do. A "gv" op is suitable if the GV's CV slot is populated. A "const" op is suitable if the constant value must be an RV pointing to a CV. Details of this process may change in future versions of Perl.
If the "rv2cv" op has the "OPpENTERSUB_AMPER" flag set then no attempt is made to identify the subroutine statically: this flag is used to suppress compile-time magic on a subroutine call, forcing it to use default runtime behaviour.
If flags has the bit "RV2CVOPCV_MARK_EARLY" set, then the handling of a GV reference is modified. If a GV was examined and its CV slot was found to be empty, then the "gv" op has the "OPpEARLY_CV" flag set. If the op is not optimised away, and the CV slot is later populated with a subroutine having a prototype, that flag eventually triggers the warning ``called too early to check prototype''.
If flags has the bit "RV2CVOPCV_RETURN_NAME_GV" set, then instead of returning a pointer to the subroutine it returns a pointer to the GV giving the most appropriate name for the subroutine in this context. Normally this is just the "CvGV" of the subroutine, but for an anonymous ("CvANON") subroutine that is referenced through a GV it will be the referencing GV. The resulting "GV*" is cast to "CV*" to be returned. A null pointer is returned as usual if there is no statically-determinable subroutine.
CV *rv2cv_op_cv(OP *cvop, U32 flags)
The C-level function pointer is returned in *ckfun_p, and an SV argument for it is returned in *ckobj_p. The function is intended to be called in this manner:
entersubop = (*ckfun_p)(aTHX_ entersubop, namegv, (*ckobj_p));
In this call, entersubop is a pointer to the "entersub" op, which may be replaced by the check function, and namegv is a GV supplying the name that should be used by the check function to refer to the callee of the "entersub" op if it needs to emit any diagnostics. It is permitted to apply the check function in non-standard situations, such as to a call to a different subroutine or to a method call.
By default, the function is Perl_ck_entersub_args_proto_or_list, and the SV parameter is cv itself. This implements standard prototype processing. It can be changed, for a particular subroutine, by ``cv_set_call_checker''.
void cv_get_call_checker(CV *cv, Perl_call_checker *ckfun_p,
SV **ckobj_p)
The C-level function pointer is supplied in ckfun, and an SV argument for it is supplied in ckobj. The function is intended to be called in this manner:
entersubop = ckfun(aTHX_ entersubop, namegv, ckobj);
In this call, entersubop is a pointer to the "entersub" op, which may be replaced by the check function, and namegv is a GV supplying the name that should be used by the check function to refer to the callee of the "entersub" op if it needs to emit any diagnostics. It is permitted to apply the check function in non-standard situations, such as to a call to a different subroutine or to a method call.
The current setting for a particular CV can be retrieved by ``cv_get_call_checker''.
void cv_set_call_checker(CV *cv, Perl_call_checker ckfun,
SV *ckobj)
OP *ck_entersub_args_list(OP *entersubop)
protosv supplies the subroutine prototype to be applied to the call. It may be a normal defined scalar, of which the string value will be used. Alternatively, for convenience, it may be a subroutine object (a "CV*" that has been cast to "SV*") which has a prototype. The prototype supplied, in whichever form, does not need to match the actual callee referenced by the op tree.
If the argument ops disagree with the prototype, for example by having an unacceptable number of arguments, a valid op tree is returned anyway. The error is reflected in the parser state, normally resulting in a single exception at the top level of parsing which covers all the compilation errors that occurred. In the error message, the callee is referred to by the name defined by the namegv parameter.
OP *ck_entersub_args_proto(OP *entersubop, GV *namegv,
SV *protosv)
protosv supplies the subroutine prototype to be applied to the call, or indicates that there is no prototype. It may be a normal scalar, in which case if it is defined then the string value will be used as a prototype, and if it is undefined then there is no prototype. Alternatively, for convenience, it may be a subroutine object (a "CV*" that has been cast to "SV*"), of which the prototype will be used if it has one. The prototype (or lack thereof) supplied, in whichever form, does not need to match the actual callee referenced by the op tree.
If the argument ops disagree with the prototype, for example by having an unacceptable number of arguments, a valid op tree is returned anyway. The error is reflected in the parser state, normally resulting in a single exception at the top level of parsing which covers all the compilation errors that occurred. In the error message, the callee is referred to by the name defined by the namegv parameter.
OP *ck_entersub_args_proto_or_list(OP *entersubop, GV *namegv,
SV *protosv)