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author | Richard Carlsson <[email protected]> | 2014-05-06 10:34:07 +0200 |
---|---|---|
committer | Hans Bolinder <[email protected]> | 2015-03-10 10:21:41 +0100 |
commit | 8e7441c27485bd416abdb0253c9c92620d671065 (patch) | |
tree | 6d722b99dd0f001346450b14903e7e6f79379ecc /lib/stdlib/doc/src/io_lib.xml | |
parent | 4037296294670e7a9bb2a3c1cdbd0236cbc15807 (diff) | |
download | otp-8e7441c27485bd416abdb0253c9c92620d671065.tar.gz otp-8e7441c27485bd416abdb0253c9c92620d671065.tar.bz2 otp-8e7441c27485bd416abdb0253c9c92620d671065.zip |
Make the scanned form of the io_lib format strings available for processing
This adds three new functions to io_lib - scan_format/2, unscan_format/1,
and build_text/1 - which expose the parsed form of the format control
sequences to make it possible to easily modify or filter the input to
io_lib:format/2. This can e.g. be used in order to replace unbounded-size
control sequences like ~w or ~p with corresponding depth-limited ~W and ~P
before doing the actual formatting.
Diffstat (limited to 'lib/stdlib/doc/src/io_lib.xml')
-rw-r--r-- | lib/stdlib/doc/src/io_lib.xml | 70 |
1 files changed, 69 insertions, 1 deletions
diff --git a/lib/stdlib/doc/src/io_lib.xml b/lib/stdlib/doc/src/io_lib.xml index 3312b08064..2117d66381 100644 --- a/lib/stdlib/doc/src/io_lib.xml +++ b/lib/stdlib/doc/src/io_lib.xml @@ -4,7 +4,7 @@ <erlref> <header> <copyright> - <year>1996</year><year>2013</year> + <year>1996</year><year>2014</year> <holder>Ericsson AB. All Rights Reserved.</holder> </copyright> <legalnotice> @@ -59,6 +59,35 @@ <datatype> <name name="latin1_string"/> </datatype> + <datatype> + <name name="format_spec"/> + <desc><p>Description:</p> + <list type="bulleted"> + <item><p><c>control_char</c> is the type of control + sequence: <c>$P</c>, <c>$w</c>, and so on;</p> + </item> + <item><p><c>args</c> is a list of the arguments used by the + control sequence, or an empty list if the control sequence + does not take any arguments;</p> + </item> + <item><p><c>width</c> is the field width;</p> + </item> + <item><p><c>adjust</c> is the adjustment;</p> + </item> + <item><p><c>precision</c> is the precision of the printed + argument;</p> + </item> + <item><p><c>pad_char</c> is the padding character;</p> + </item> + <item><p><c>encoding</c> is set to <c>true</c> if the translation + modifier <c>t</c> is present;</p> + </item> + <item><p><c>strings</c> is set to <c>false</c> if the modifier + <c>l</c> is present.</p> + </item> + </list> + </desc> + </datatype> </datatypes> <funcs> <func> @@ -260,6 +289,45 @@ </desc> </func> <func> + <name name="scan_format" arity="2"/> + <fsummary>Parse all control sequences in the format string</fsummary> + <desc> + <p>Returns a list corresponding to the given format string, + where control sequences have been replaced with + corresponding tuples. This list can be passed to <seealso + marker="#build_text/1">io_lib:build_text/1</seealso> to have + the same effect as <c>io_lib:format(Format, Args)</c>, or to + <seealso + marker="#unscan_format/1">io_lib:unscan_format/1</seealso> + in order to get the corresponding pair of <c>Format</c> and + <c>Args</c> (with every <c>*</c> and corresponding argument + expanded to numeric values).</p> + <p>A typical use of this function is to replace unbounded-size + control sequences like <c>~w</c> and <c>~p</c> with the + depth-limited variants <c>~W</c> and <c>~P</c> before + formatting to text, e.g. in a logger.</p> + </desc> + </func> + <func> + <name name="unscan_format" arity="1"/> + <fsummary>Revert a pre-parsed format list to a plain character list + and a list of arguments</fsummary> + <desc> + <p>See <seealso + marker="#scan_format/2">io_lib:scan_format/2</seealso> for + details.</p> + </desc> + </func> + <func> + <name name="build_text" arity="1"/> + <fsummary>Build the output text for a pre-parsed format list</fsummary> + <desc> + <p>See <seealso + marker="#scan_format/2">io_lib:scan_format/2</seealso> for + details.</p> + </desc> + </func> + <func> <name name="indentation" arity="2"/> <fsummary>Indentation after printing string</fsummary> <desc> |