13.  Appendix A: Functions that can Trigger a Garbage Collection  

      This appendix lists the functions exported by Elk that may trigger a garbage collection. Within C/C++ code, local Scheme objects must be protected as shown in section @(ch-gc) when one of these functions is called during the objects' lifetime.

      The C functions corresponding to the following Scheme primitives can cause a garbage collection:

append                  load                    read-string
apply                   macro-body              require
autoload                macro-expand            reverse
backtrace-list          make-list               string
call-with-input-file    make-string             string->list
call-with-output-file   make-vector             string->number
call/cc                 map                     string->symbol
command-line-args       oblist                  string-append
cons                    open-input-file         string-copy
dump                    open-input-output-file  substring
dynamic-wind            open-input-string       symbol-plist
eval                    open-output-file        tilde-expand
for-each                open-output-string      type
force                   port-line-number        vector
get-output-string       procedure-lambda        vector->list
list                    provide                 vector-copy
list->string            put                     with-input-from-file
list->vector            read                    with-output-to-file

all special forms
all mathematical primitives except predicates
all output primitives if output is sent to a string port

      In practice, most of these functions, in particular the special forms, are rarely or never used in extensions or Elk-based applications. In addition to these primitives, the following C functions can trigger a garbage collection:

Alloc_Object()          Make_Reduced_Flonum()   Make_String()
Make_Port()             Make_Flonum()           Make_Const_String()
Load_Source_Port()      Define_Primitive()      Intern()
Load_File()             Printf()                CI_Intern()
Copy_List()             Print_Object()          Define_Variable()
Const_Cons()            General_Print_Object()  Define_Symbol()
Make_Integer()          Format()                Bits_To_Symbols()
Make_Unsigned()         Eval()                  Make_Vector()
Make_Long()             Funcall()               Make_Const_Vector()
Make_Unsigned_Long()

Note: Make_Integer(), Make_Unsigned(), Make_Long(), and Make_Unsigned_Long() can only trigger a garbage collection if FIXNUM_FITS() (or UFIXNUM_FITS(), respectively) returns zero for the given argument.


Markup created by unroff 1.0,    September 24, 1996,    net@informatik.uni-bremen.de