Author: Jan Nijtmans <[email protected]>
State: Draft
Type: Project
Created: 11-05-2023
Tcl-Version: 9.1
Tcl-Branch: tip-668
Abstract
The normal functions Tcl_Alloc(), Tcl_Realloc() (and a few more)
result in a Panic when the memory allocation fails. There are
alternative functions Tcl_AtteptAlloc()/Tcl_AttemptRealloc()
which return a NULL-pointer in this case. The advantage of the
Attempt form of those functions is that we no longer have to
check before the function-call whether the size parameter
isn't too big, we can just make the call and check afterwards
whether it was possible or not. This TIP proposes to make this
behavior available to the normal Tcl_Alloc()/Tcl_Realloc()
Rationale
TODO
Implementation
The functions Tcl_Alloc(), Tcl_Realloc() have been removed,
and Tcl_AtteptAlloc()/Tcl_AttemptRealloc() renamed to
Tcl_Alloc(), Tcl_Realloc(). This means that everything will
keep functioning as before. The only visible change is that
instead of panicing, those functions might unexpectedly
return a NULL-pointer. Most likely, those null-pointers
eventually result in a null-pointer-exception, which is
just as bad as panicing.
Implementation is in Tcl branch "tip-668".
Eventually all Tcl_Alloc(), Tcl_Realloc() calls should
check their result, and handle a clean recovery when
allocation fails. Some newer code (like the improved list
implementation) already does that by using the Attempt*
functions. This change eliminates the need for special
Attempt*-functions, it just provides this for all
normal functions. This makes Tcl_Alloc()/Tcl_Realloc()
behave the same as the standard C malloc(), realloc(),
which also return a null-pointer on failure.
TODO
Compatibility
TODO
Copyright
This document has been placed in the public domain.