Common-Lisp printing the tab character in function format

问题

I wish to print the tab character with the format function. I can achieve this with ~C and then placing #\tab as an argument to format, but this seems a bit verbose as for a newline one can simply place a ~% in the string.

• What is the most commonly used practise for printing tabs with the format function?

Thanks for all the help!

回答1:

There is no notation for the tab character in FORMAT.

There are several choices, but none is really really good.

• use #\tab (or a variable set to the character) as the argument, as you mention, is okay for me

• embed a literal tab character in the string. This may break with some editor settings, where the editor replaces tabs with spaces. It's also not directly visible.

• use a function in a format string, which writes a tab character

• use a reader macro to introduce extended string syntax. Probably not bad. Maybe there exists even one. There was a post on comp.lang.lisp with an example.

来源：https://stackoverflow.com/questions/23577195/common-lisp-printing-the-tab-character-in-function-format