[ViewVC] Contents 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 cnanot 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:	1.2
Committed:	Thu Aug 18 19:36:32 2011 UTC (12 years, 9 months ago) by root
Branch:	MAIN
CVS Tags:	rel-1_1
Changes since 1.1:	+31 -1 lines
Log Message:	1.1
#	Content
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	$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	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	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	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	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	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	which cnanot be passed directly. Remember that taking a reference of
134	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