Subject: Re: How to read from a file which has `:'? From: Erik Naggum <email@example.com> Date: 1997/10/01 Newsgroups: comp.lang.lisp Message-ID: <firstname.lastname@example.org> * email@example.com | I have to read from a file (a stream) which contains some text with | numbers, so I want the numbers to be parsed, but I don't want to be | pestered by error messages that #zzz is undefined and xxx is not a valid | package name (when the file has "xxx:" in it). bind a reader macro to each character that is to be considered text, and assemble a _string_ from the read characters, instead. you can still use `read', but you don't want the normal Lisp reader. anyway, this is a lot easier if you pull the whole file into memory with `read-sequence' first, since you can return (displaced) substrings of the file instead of consing up new strings all the time. but even this is wasteful if you have very large files. (it also isn't possible in some smaller Lisp implementations that think `fixnum' should be 16 bits wide.) I'd actually love to see a `stream-substring' function that could return an arbitrary segment of a stream's contents from a position set as the `stream-mark' to anywhere between the mark and the current position. the most common way to use I/O buffers is to allocate one for a given direction and reuse it as the buffer is exhausted at the character level. I suggest the buffers should be kept around if a (structured) input token crosses a buffer boundary, the start of which be maintained by the mark. the I/O system would keep allocating I/O buffers until the mark moved, and free them when it moved out of them. this would make it possible to grab strings from an input stream without having to copy each character from one string to another, which probably would have to be adjustable, too. this isn't only a question of performance. I don't think collecting characters into a string one by one from another string is elegant. #\Erik -- if you think this year is "97", _you_ are not "year 2000 compliant". see http://www.naggum.no/emacs/ for Emacs-20-related material.