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installUnicodeWidthTable: improve documentation

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Jonathan Daugherty 2020-03-03 13:12:18 -08:00
parent 1545df3207
commit 36b72dc2ed
1 changed files with 20 additions and 9 deletions
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29
src/Graphics/Vty/UnicodeWidthTable/Install.hs
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@ -37,15 +37,26 @@ tableSize = 0x110000
-- | Install a custom unicode character width table.
--
-- This affects the behavior of the 'wcwidth' function and functions
-- that call it. It does so by changing global state available to the C
-- implementation of 'wcwidth'. To ensure that your program gets consistent
-- results from evaluating calls to 'wcwidth', the installation of a
-- custom table should be performed before you call 'wcwidth' in your
-- program. This is best done at Vty startup. It's also important to
-- note that once a custom table has been installed, it is permanent for
-- the life of the process. No new table can be installed, and the new
-- custom table cannot be removed.
-- This affects the behavior of the 'Graphics.Vty.Image.wcwidth'
-- function and functions that call it. It does so by
-- changing global state available to the C implementation
-- of 'Graphics.Vty.Image.wcwidth'. To ensure that your
-- program gets consistent results from evaluating calls to
-- 'Graphics.Vty.Image.wcwidth', the installation of a custom table
-- should be performed before you call 'Graphics.Vty.Image.wcwidth' in
-- your program.
--
-- This is best done at Vty startup, and if you use
-- 'Graphics.Vty.mkVty', that function calls this automatically based on
-- the Vty configuration's declared width tables. It is exposed as part
-- of the public API so that applications can call this as needed if
-- they don't want to control the terminal with 'mkVty' but do want to
-- make calls to 'Graphics.Vty.Image.wcwidth'.
--
-- It's also important to note that once a
-- custom table has been installed, it is permanent for the life of the
-- process. No new table can be installed, and the new custom table
-- cannot be removed.
--
-- If this function fails for any reason -- if the table cannot be
-- installed or is invalid, or if a custom table already exists -- this