From b39cafaa22ad7efc2ac4b64a5eeac8f49bc80e00 Mon Sep 17 00:00:00 2001 From: Tanaka Akira Date: Mon, 31 May 1999 17:10:16 +0000 Subject: Initial revision --- Doc/Zsh/mod_mapfile.yo | 46 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 46 insertions(+) create mode 100644 Doc/Zsh/mod_mapfile.yo (limited to 'Doc') diff --git a/Doc/Zsh/mod_mapfile.yo b/Doc/Zsh/mod_mapfile.yo new file mode 100644 index 000000000..6d0475711 --- /dev/null +++ b/Doc/Zsh/mod_mapfile.yo @@ -0,0 +1,46 @@ +texinode(The mapfile Module)(The parameter Module)(The files Module)(Zsh Modules) +sect(The mapfile Module) +cindex(parameter, file access via) +The tt(mapfile) module provides one special associative array parameter of +the same name. + +startitem() +vindex(mapfile) +item(tt(mapfile))( +This associative array takes as keys the names of files; the resulting +value is the content of the file. The value is treated identically to any +other text coming from a parameter. The value may also be assigned to, in +which case the file in question is written (whether or not it originally +existed); or an element may be unset, which will delete the file in +question. For example, `tt(vared mapfile[myfile])' works as expected, +editing the file `tt(myfile)'. + +When the array is accessed as a whole, the keys are the names of files in +the current directory, and the values are empty (to save a huge overhead in +memory). Thus tt(${(k)mapfile}) has the same affect as the glob operator +tt(*(D)), since files beginning with a dot are not special. Care must be +taken with expressions such as tt(rm ${(k)mapfile}), which will delete +every file in the current directory without the usual `tt(rm *)' test. + +The parameter tt(mapfile) may be made read-only; in that case, files +referenced may not be written or deleted. +) +enditem() + +subsect(Limitations) + +Although reading and writing of the file in question is efficiently +handled, zsh's internal memory management may be arbitrarily baroque. Thus +it should not automatically be assumed that use of tt(mapfile) represents a +gain in efficiency over use of other mechanisms. Note in particular that +the whole contents of the file will always reside physically in memory when +accessed (possibly multiple times, due to standard parameter subsitution +operations). + +No errors are printed or flagged for non-existent, unreadable, or +unwriteable files, as the parameter mechanism is too low in the shell +execution hierarchy to make this convenient. + +It is unfortunate that the mechanism for loading modules does not yet allow +the user to specify the name of the shell parameter to be given the special +behaviour. -- cgit 1.4.1