[ViewVC] Annotation of: cvs/Convert-Scalar/README

NAME
    Convert::Scalar - convert between different representations of perl
    scalars

SYNOPSIS
     use Convert::Scalar;

DESCRIPTION
    This module exports various internal perl methods that change the
    internal representation or state of a perl scalar. All of these work
    in-place, that is, they modify their scalar argument. No functions are
    exported by default.

    The following export tags exist:

     :utf8   all functions with utf8 in their name
     :taint  all functions with taint in their name
     :refcnt all functions with refcnt in their name
     :ok     all *ok-functions.

    utf8 scalar[, mode]
        Returns true when the given scalar is marked as utf8, false
        otherwise. If the optional mode argument is given, also forces the
        interpretation of the string to utf8 (mode true) or plain bytes
        (mode false). The actual (byte-) content is not changed. The return
        value always reflects the state before any modification is done.

        This function is useful when you "import" utf8-data into perl, or
        when some external function (e.g. storing/retrieving from a
        database) removes the utf8-flag.

    utf8_on scalar
        Similar to "utf8 scalar, 1", but additionally returns the scalar
        (the argument is still modified in-place).

    utf8_off scalar
        Similar to "utf8 scalar, 0", but additionally returns the scalar
        (the argument is still modified in-place).

    utf8_valid scalar [Perl 5.7]
        Returns true if the bytes inside the scalar form a valid utf8
        string, false otherwise (the check is independent of the actual
        encoding perl thinks the string is in).

    utf8_upgrade scalar
        Convert the string content of the scalar in-place to its
        UTF8-encoded form (and also returns it).

    utf8_downgrade scalar[, fail_ok=0]
        Attempt to convert the string content of the scalar from
        UTF8-encoded to ISO-8859-1. This may not be possible if the string
        contains characters that cannot be represented in a single byte; if
        this is the case, it leaves the scalar unchanged and either returns
        false or, if "fail_ok" is not true (the default), croaks.

    utf8_encode scalar
        Convert the string value of the scalar to UTF8-encoded, but then
        turn off the "SvUTF8" flag so that it looks like bytes to perl
        again. (Might be removed in future versions).

    utf8_length scalar
        Returns the number of characters in the string, counting wide UTF8
        characters as a single character, independent of wether the scalar
        is marked as containing bytes or mulitbyte characters.

    $old = readonly scalar[, $new]
        Returns whether the scalar is currently readonly, and sets or clears
        the readonly status if a new status is given.

    readonly_on scalar
        Sets the readonly flag on the scalar.

    readonly_off scalar
        Clears the readonly flag on the scalar.

    unmagic scalar, type
        Remove the specified magic from the scalar (DANGEROUS!).

    weaken scalar
        Weaken a reference. (See also WeakRef).

    taint scalar
        Taint the scalar.

    tainted scalar
        returns true when the scalar is tainted, false otherwise.

    untaint scalar
        Remove the tainted flag from the specified scalar.

    length = len scalar
        Returns SvLEN (scalar), that is, the actual number of bytes
        allocated to the string value, or "undef", is the scalar has no
        string value.

    scalar = grow scalar, newlen
        Sets the memory area used for the scalar to the given length, if the
        current length is less than the new value. This does not affect the
        contents of the scalar, but is only useful to "pre-allocate" memory
        space if you know the scalar will grow. The return value is the
        modified scalar (the scalar is modified in-place).

    scalar = extend scalar, addlen
        Reserves enough space in the scalar so that addlen bytes can be
        appended without reallocating it. The actual contents of the scalar
        will not be affected. The modified scalar will also be returned.

        This function is meant to make append workloads efficient - if you
        append a short string to a scalar many times (millions of times),
        then perl will have to reallocate and copy the scalar basically
        every time.

        If you instead use "extend $scalar, length $shortstring", then
        Convert::Scalar will use a "size to next power of two, roughly"
        algorithm, so as the scalar grows, perl will have to resize and copy
        it less and less often.

    refcnt scalar[, newrefcnt]
        Returns the current reference count of the given scalar and
        optionally sets it to the given reference count.

    refcnt_inc scalar
        Increments the reference count of the given scalar inplace.

    refcnt_dec scalar
        Decrements the reference count of the given scalar inplace. Use
        "weaken" instead if you understand what this function is fore.
        Better yet: don't use this module in this case.

    refcnt_rv scalar[, newrefcnt]
        Works like "refcnt", but dereferences the given reference first.
        This is useful to find the reference count of arrays or hashes,
        which cannot be passed directly. Remember that taking a reference of
        some object increases it's reference count, so the reference count
        used by the *_rv-functions tend to be one higher.

    refcnt_inc_rv scalar
        Works like "refcnt_inc", but dereferences the given reference first.

    refcnt_dec_rv scalar
        Works like "refcnt_dec", but dereferences the given reference first.

    ok scalar
    uok scalar
    rok scalar
    pok scalar
    nok scalar
    niok scalar
        Calls SvOK, SvUOK, SvROK, SvPOK, SvNOK or SvNIOK on the given
        scalar, respectively.

  CANDIDATES FOR FUTURE RELEASES
    The following API functions (perlapi) are considered for future
    inclusion in this module If you want them, write me.

     sv_upgrade
     sv_pvn_force
     sv_pvutf8n_force
     the sv2xx family

AUTHOR
     Marc Lehmann <schmorp@schmorp.de>
     http://home.schmorp.de/

Revision:	1.3
Committed:	Thu Jun 25 14:04:32 2015 UTC (10 years, 4 months ago) by root
Branch:	MAIN
CVS Tags:	rel-1_11
Changes since 1.2:	+1 -1 lines
Log Message:	1.11
#	User	Rev	Content
1	root	1.1	NAME
2			Convert::Scalar - convert between different representations of perl
3			scalars
4
5			SYNOPSIS
6			use Convert::Scalar;
7
8			DESCRIPTION
9			This module exports various internal perl methods that change the
10			internal representation or state of a perl scalar. All of these work
11			in-place, that is, they modify their scalar argument. No functions are
12			exported by default.
13
14			The following export tags exist:
15
16			:utf8 all functions with utf8 in their name
17			:taint all functions with taint in their name
18			:refcnt all functions with refcnt in their name
19			:ok all *ok-functions.
20
21			utf8 scalar[, mode]
22			Returns true when the given scalar is marked as utf8, false
23			otherwise. If the optional mode argument is given, also forces the
24			interpretation of the string to utf8 (mode true) or plain bytes
25			(mode false). The actual (byte-) content is not changed. The return
26			value always reflects the state before any modification is done.
27
28			This function is useful when you "import" utf8-data into perl, or
29			when some external function (e.g. storing/retrieving from a
30			database) removes the utf8-flag.
31
32			utf8_on scalar
33			Similar to "utf8 scalar, 1", but additionally returns the scalar
34			(the argument is still modified in-place).
35
36			utf8_off scalar
37			Similar to "utf8 scalar, 0", but additionally returns the scalar
38			(the argument is still modified in-place).
39
40			utf8_valid scalar [Perl 5.7]
41			Returns true if the bytes inside the scalar form a valid utf8
42			string, false otherwise (the check is independent of the actual
43			encoding perl thinks the string is in).
44
45			utf8_upgrade scalar
46			Convert the string content of the scalar in-place to its
47			UTF8-encoded form (and also returns it).
48
49			utf8_downgrade scalar[, fail_ok=0]
50			Attempt to convert the string content of the scalar from
51			UTF8-encoded to ISO-8859-1. This may not be possible if the string
52			contains characters that cannot be represented in a single byte; if
53			this is the case, it leaves the scalar unchanged and either returns
54			false or, if "fail_ok" is not true (the default), croaks.
55
56			utf8_encode scalar
57			Convert the string value of the scalar to UTF8-encoded, but then
58			turn off the "SvUTF8" flag so that it looks like bytes to perl
59			again. (Might be removed in future versions).
60
61			utf8_length scalar
62			Returns the number of characters in the string, counting wide UTF8
63			characters as a single character, independent of wether the scalar
64			is marked as containing bytes or mulitbyte characters.
65
66	root	1.2	$old = readonly scalar[, $new]
67			Returns whether the scalar is currently readonly, and sets or clears
68			the readonly status if a new status is given.
69
70			readonly_on scalar
71			Sets the readonly flag on the scalar.
72
73			readonly_off scalar
74			Clears the readonly flag on the scalar.
75
76	root	1.1	unmagic scalar, type
77			Remove the specified magic from the scalar (DANGEROUS!).
78
79			weaken scalar
80			Weaken a reference. (See also WeakRef).
81
82			taint scalar
83			Taint the scalar.
84
85			tainted scalar
86			returns true when the scalar is tainted, false otherwise.
87
88			untaint scalar
89			Remove the tainted flag from the specified scalar.
90
91	root	1.2	length = len scalar
92			Returns SvLEN (scalar), that is, the actual number of bytes
93			allocated to the string value, or "undef", is the scalar has no
94			string value.
95
96			scalar = grow scalar, newlen
97	root	1.1	Sets the memory area used for the scalar to the given length, if the
98			current length is less than the new value. This does not affect the
99			contents of the scalar, but is only useful to "pre-allocate" memory
100			space if you know the scalar will grow. The return value is the
101			modified scalar (the scalar is modified in-place).
102
103	root	1.2	scalar = extend scalar, addlen
104			Reserves enough space in the scalar so that addlen bytes can be
105			appended without reallocating it. The actual contents of the scalar
106			will not be affected. The modified scalar will also be returned.
107
108			This function is meant to make append workloads efficient - if you
109			append a short string to a scalar many times (millions of times),
110			then perl will have to reallocate and copy the scalar basically
111			every time.
112
113			If you instead use "extend $scalar, length $shortstring", then
114			Convert::Scalar will use a "size to next power of two, roughly"
115			algorithm, so as the scalar grows, perl will have to resize and copy
116			it less and less often.
117
118	root	1.1	refcnt scalar[, newrefcnt]
119			Returns the current reference count of the given scalar and
120			optionally sets it to the given reference count.
121
122			refcnt_inc scalar
123			Increments the reference count of the given scalar inplace.
124
125			refcnt_dec scalar
126			Decrements the reference count of the given scalar inplace. Use
127			"weaken" instead if you understand what this function is fore.
128			Better yet: don't use this module in this case.
129
130			refcnt_rv scalar[, newrefcnt]
131			Works like "refcnt", but dereferences the given reference first.
132			This is useful to find the reference count of arrays or hashes,
133	root	1.3	which cannot be passed directly. Remember that taking a reference of
134	root	1.1	some object increases it's reference count, so the reference count
135			used by the *_rv-functions tend to be one higher.
136
137			refcnt_inc_rv scalar
138			Works like "refcnt_inc", but dereferences the given reference first.
139
140			refcnt_dec_rv scalar
141			Works like "refcnt_dec", but dereferences the given reference first.
142
143			ok scalar
144			uok scalar
145			rok scalar
146			pok scalar
147			nok scalar
148			niok scalar
149			Calls SvOK, SvUOK, SvROK, SvPOK, SvNOK or SvNIOK on the given
150			scalar, respectively.
151
152			CANDIDATES FOR FUTURE RELEASES
153			The following API functions (perlapi) are considered for future
154			inclusion in this module If you want them, write me.
155
156			sv_upgrade
157			sv_pvn_force
158			sv_pvutf8n_force
159			the sv2xx family
160
161			AUTHOR
162			Marc Lehmann <schmorp@schmorp.de>
163			http://home.schmorp.de/
164