{"id":7257,"date":"2022-12-20T19:36:01","date_gmt":"2022-12-20T22:36:01","guid":{"rendered":"http:\/\/lode.uno\/linux-man\/index.php\/2022\/12\/20\/nre-man3-4\/"},"modified":"2022-12-20T19:36:01","modified_gmt":"2022-12-20T22:36:01","slug":"nre-man3-4","status":"publish","type":"post","link":"https:\/\/lode.uno\/linux-man\/2022\/12\/20\/nre-man3-4\/","title":{"rendered":"NRE (man3)"},"content":{"rendered":"

NRE<\/h1>\n

NAME<\/a>
SYNOPSIS<\/a>
ARGUMENTS<\/a>
DESCRIPTION<\/a>
EXAMPLE<\/a>
SEE ALSO<\/a>
KEYWORDS<\/a>
COPYRIGHT<\/a> <\/p>\n

\n

______________________________________________________________________________<\/p>\n

NAME <\/a> <\/h2>\n

Tcl_NRCreateCommand, Tcl_NRCallObjProc, Tcl_NREvalObj, Tcl_NREvalObjv, Tcl_NRCmdSwap, Tcl_NRExprObj, Tcl_NRAddCallback \u2212 Non-Recursive (stackless) evaluation of Tcl scripts.<\/p>\n

SYNOPSIS <\/a> <\/h2>\n

#include <\/b><\/p>\n

Tcl_Command
Tcl_NRCreateCommand<\/b>(interp, cmdName, proc, nreProc, clientData,
deleteProc<\/i>)<\/p>\n

int
Tcl_NRCallObjProc<\/b>(interp, nreProc, clientData, objc, objv<\/i>)<\/p>\n

int
Tcl_NREvalObj<\/b>(interp, objPtr, flags<\/i>)<\/p>\n

int
Tcl_NREvalObjv<\/b>(interp, objc, objv, flags<\/i>)<\/p>\n

int
Tcl_NRCmdSwap<\/b>(interp, cmd, objc, objv, flags<\/i>)<\/p>\n

int
Tcl_NRExprObj<\/b>(interp, objPtr, resultPtr<\/i>)<\/p>\n

void
Tcl_NRAddCallback<\/b>(interp, postProcPtr, data0, data1, data2, data3<\/i>)<\/p>\n

ARGUMENTS <\/a> <\/h2>\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n
<\/td>\n\n

Tcl_Interp *interp<\/i> (in)<\/p>\n<\/td>\n

<\/td>\n\n

The relevant Interpreter.<\/p>\n<\/td>\n<\/tr>\n

<\/td>\n\n

char *cmdName<\/i> (in)<\/p>\n<\/td>\n

<\/td>\n\n

Name of the command to create.<\/p>\n<\/td>\n<\/tr>\n

<\/td>\n\n

Tcl_ObjCmdProc *proc<\/i> (in)<\/p>\n<\/td>\n

<\/td>\n\n

Called in order to evaluate a command. Is often just a small wrapper that uses Tcl_NRCallObjProc<\/b> to call nreProc<\/i> using a new trampoline. Behaves in the same way as the proc<\/i> argument to Tcl_CreateObjCommand<\/b>(3) (q.v.<\/i>).<\/p>\n<\/td>\n<\/tr>\n

<\/td>\n\n

Tcl_ObjCmdProc *nreProc<\/i> (in)<\/p>\n<\/td>\n

<\/td>\n\n

Called instead of proc<\/i> when a trampoline is already in use.<\/p>\n<\/td>\n<\/tr>\n

<\/td>\n\n

ClientData clientData<\/i> (in)<\/p>\n<\/td>\n

<\/td>\n\n

Arbitrary one-word value passed to proc<\/i>, nreProc<\/i>, deleteProc<\/i> and objProc<\/i>.<\/p>\n<\/td>\n<\/tr>\n

<\/td>\n\n

Tcl_CmdDeleteProc *deleteProc<\/i> (in\/out)<\/p>\n<\/td>\n

<\/td>\n\n

Called before cmdName<\/i> is deleted from the interpreter, allowing for command-specific cleanup. May be NULL.<\/p>\n<\/td>\n<\/tr>\n

<\/td>\n\n

int objc<\/i> (in)<\/p>\n<\/td>\n

<\/td>\n\n

Number of items in objv<\/i>.<\/p>\n<\/td>\n<\/tr>\n

<\/td>\n\n

Tcl_Obj **objv<\/i> (in)<\/p>\n<\/td>\n

<\/td>\n\n

Words in the command.<\/p>\n<\/td>\n<\/tr>\n

<\/td>\n\n

Tcl_Obj *objPtr<\/i> (in)<\/p>\n<\/td>\n

<\/td>\n\n

A script or expression to evaluate.<\/p>\n<\/td>\n<\/tr>\n

<\/td>\n\n

int flags<\/i> (in)<\/p>\n<\/td>\n

<\/td>\n\n

As described for Tcl_EvalObjv<\/i>.<\/p>\n<\/td>\n<\/tr>\n

<\/td>\n\n

Tcl_Command cmd<\/i> (in)<\/p>\n<\/td>\n

<\/td>\n\n

Token to use instead of one derived from the first word of objv<\/i> in order to evaluate a command.<\/p>\n<\/td>\n<\/tr>\n

<\/td>\n\n

Tcl_Obj *resultPtr<\/i> (out)<\/p>\n<\/td>\n

<\/td>\n\n

Pointer to an unshared Tcl_Obj where the result of the evaluation is stored if the return code is TCL_OK.<\/p>\n<\/td>\n<\/tr>\n

<\/td>\n\n

Tcl_NRPostProc *postProcPtr<\/i> (in)<\/p>\n<\/td>\n

<\/td>\n\n

A function to push.<\/p>\n<\/td>\n<\/tr>\n

<\/td>\n\n

ClientData data0<\/i> (in)<\/p>\n<\/td>\n

<\/td>\n <\/td>\n<\/tr>\n
<\/td>\n\n

ClientData data1<\/i> (in)<\/p>\n<\/td>\n

<\/td>\n <\/td>\n<\/tr>\n
<\/td>\n\n

ClientData data2<\/i> (in)<\/p>\n<\/td>\n

<\/td>\n <\/td>\n<\/tr>\n
<\/td>\n\n

ClientData data3<\/i> (in)<\/p>\n<\/td>\n

<\/td>\n\n

data0<\/i> through data3<\/i> are four one-word values that will be passed to the function designated by postProcPtr<\/i> when it is invoked.<\/p>\n<\/td>\n<\/tr>\n<\/table>\n

______________________________________________________________________________<\/p>\n

DESCRIPTION <\/a> <\/h2>\n

These functions provide an interface to the function stack that an interpreter iterates through to evaluate commands. The routine behind a command is implemented by an initial function and any additional functions that the routine pushes onto the stack as it progresses. The interpreter itself pushes functions onto the stack to react to the end of a routine and to exercise other forms of control such as switching between in-progress stacks and the evaluation of other scripts at additional levels without adding frames to the C stack. To execute a routine, the initial function for the routine is called and then a small bit of code called a trampoline<\/i> iteratively takes functions off the stack and calls them, using the value of the last call as the value of the routine.<\/p>\n

Tcl_NRCallObjProc<\/b> calls nreProc<\/i> using a new trampoline.<\/p>\n

Tcl_NRCreateCommand<\/b>, an alternative to Tcl_CreateObjCommand<\/b>, resolves cmdName<\/i>, which may contain namespace qualifiers, relative to the current namespace, creates a command by that name, and returns a token for the command which may be used in subsequent calls to Tcl_GetCommandName<\/b>. Except for a few cases noted below any existing command by the same name is first deleted. If interp<\/i> is in the process of being deleted Tcl_NRCreateCommand<\/b> does not create any command, does not delete any command, and returns NULL.<\/p>\n

Tcl_NREvalObj<\/b> pushes a function that is like Tcl_EvalObjEx<\/b> but consumes no space on the C stack.<\/p>\n

Tcl_NREvalObjv<\/b> pushes a function that is like Tcl_EvalObjv<\/b> but consumes no space on the C stack.<\/p>\n

Tcl_NRCmdSwap<\/b> is like Tcl_NREvalObjv<\/b>, but uses cmd<\/i>, a token previously returned by Tcl_CreateObjCommand<\/b> or Tcl_GetCommandFromObj<\/b>, instead of resolving the first word of objv<\/i>.<\/p>\n

Tcl_NRExprObj<\/b> pushes a function that evaluates objPtr<\/i> as an expression in the same manner as Tcl_ExprObj<\/b> but without consuming space on the C stack.<\/p>\n

All of the functions return TCL_OK<\/b> if the evaluation of the script, command, or expression has been scheduled successfully. Otherwise (for example if the command name cannot be resolved), they return TCL_ERROR<\/b> and store a message as the interpreter\u2019s result.<\/p>\n

Tcl_NRAddCallback<\/b> pushes postProcPtr<\/i>. The signature for Tcl_NRPostProc<\/b> is:<\/p>\n

typedef int
Tcl_NRPostProc<\/b>(
ClientData<\/b> data<\/i>[],
Tcl_Interp<\/b> *interp<\/i>,
int result<\/i>);<\/p>\n

data<\/i> is a pointer to an array containing data0<\/i> through data3<\/i>. result<\/i> is the value returned by the previous function implementing part the routine.<\/p>\n

EXAMPLE <\/a> <\/h2>\n

The following command uses Tcl_EvalObjEx<\/b>, which consumes space on the C stack, to evalute a script:<\/p>\n

int
TheCmdOldObjProc<\/i>(
ClientData clientData,
Tcl_Interp *interp,
int objc,
Tcl_Obj *const objv[])
{
int result;
Tcl_Obj *objPtr;<\/p>\n

… preparation …<\/i><\/p>\n

result = Tcl_EvalObjEx<\/b>(interp, objPtr, 0);<\/p>\n

… postprocessing …<\/i><\/p>\n

return result;
}
Tcl_CreateObjCommand<\/b>(interp, “theCommand”,
TheCmdOldObjProc<\/i>, clientData, TheCmdDeleteProc);<\/p>\n

To avoid consuming space on the C stack, TheCmdOldObjProc<\/i> is renamed to TheCmdNRObjProc<\/i> and the postprocessing step is split into a separate function, TheCmdPostProc<\/i>, which is pushed onto the function stack. Tcl_EvalObjEx<\/i> is replaced with Tcl_NREvalObj<\/i>, which uses a trampoline instead of consuming space on the C stack. A new version of TheCmdOldObjProc<\/i> is just a a wrapper that uses Tcl_NRCallObjProc<\/b> to call TheCmdNRObjProc<\/i>:<\/p>\n

int
TheCmdOldObjProc<\/i>(
ClientData clientData,
Tcl_Interp *interp,
int objc,
Tcl_Obj *const objv[])
{
return Tcl_NRCallObjProc<\/b>(interp, TheCmdNRObjProc<\/i>,
clientData, objc, objv);
}<\/p>\n

int
TheCmdNRObjProc<\/i>
ClientData clientData,
Tcl_Interp *interp,
int objc,
Tcl_Obj *const objv[])
{
Tcl_Obj *objPtr;<\/p>\n

… preparation …<\/i><\/p>\n

Tcl_NRAddCallback<\/b>(interp, TheCmdPostProc<\/i>,
data0, data1, data2, data3);
\/bin \/boot \/dead.letter \/dev \/etc \/home \/initrd \/lib \/lib64 \/lost+found \/media \/mnt \/opt \/proc \/release-notes.html \/release-notes.txt \/root \/run \/sbin \/srv \/sys \/tmp \/usr \/var data0 .. data3<\/i> are up to four one-word items to
bodies manpages.csv script_extrae_body.sh script.sh usr pass to the postprocessing procedure *\/<\/p>\n

return Tcl_NREvalObj<\/b>(interp, objPtr, 0);
}<\/p>\n

int
TheCmdNRPostProc<\/i>(
ClientData data[],
Tcl_Interp *interp,
int result)
{
\/bin \/boot \/dead.letter \/dev \/etc \/home \/initrd \/lib \/lib64 \/lost+found \/media \/mnt \/opt \/proc \/release-notes.html \/release-notes.txt \/root \/run \/sbin \/srv \/sys \/tmp \/usr \/var data[0] .. data[3]<\/i> are the four words of data
bodies manpages.csv script_extrae_body.sh script.sh usr passed to Tcl_NRAddCallback<\/b> *\/<\/p>\n

… postprocessing …<\/i><\/p>\n

return result;
}<\/p>\n

Any function comprising a routine can push other functions, making it possible implement looping and sequencing constructs using the function stack.<\/p>\n

SEE ALSO <\/a> <\/h2>\n

Tcl_CreateCommand(3), Tcl_CreateObjCommand(3), Tcl_EvalObjEx(3), Tcl_GetCommandFromObj(3), Tcl_ExprObj(3)<\/p>\n

KEYWORDS <\/a> <\/h2>\n

stackless, nonrecursive, execute, command, global, value, result, script<\/p>\n

COPYRIGHT <\/a> <\/h2>\n

Copyright (c) 2008 by Kevin B. Kenny. Copyright (c) 2018 by Nathan Coulter.<\/p>\n

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Tcl_NRCreateCommand, Tcl_NRCallObjProc, Tcl_NREvalObj, Tcl_NREvalObjv, Tcl_NRCmdSwap, Tcl_NRExprObj, Tcl_NRAddCallback \u2212 Non-Recursive (stackless) evaluation of Tcl scripts. <\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[2536],"tags":[2538,3007,3582],"class_list":["post-7257","post","type-post","status-publish","format-standard","hentry","category-3-llamadas-de-bibliotecas","tag-2538","tag-man3","tag-tcl_nraddcallback"],"gutentor_comment":0,"_links":{"self":[{"href":"https:\/\/lode.uno\/linux-man\/wp-json\/wp\/v2\/posts\/7257","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/lode.uno\/linux-man\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/lode.uno\/linux-man\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/lode.uno\/linux-man\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/lode.uno\/linux-man\/wp-json\/wp\/v2\/comments?post=7257"}],"version-history":[{"count":0,"href":"https:\/\/lode.uno\/linux-man\/wp-json\/wp\/v2\/posts\/7257\/revisions"}],"wp:attachment":[{"href":"https:\/\/lode.uno\/linux-man\/wp-json\/wp\/v2\/media?parent=7257"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/lode.uno\/linux-man\/wp-json\/wp\/v2\/categories?post=7257"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/lode.uno\/linux-man\/wp-json\/wp\/v2\/tags?post=7257"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}