[ViewVC] Annotation of: cvs/Geo-LatLon2Place/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=64
        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.

    nread = extend_read fh, scalar, addlen=64
        Calls "extend scalar, addlen" to ensure some space is available,
        then do the equivalent of "sysread" to the end, to try to fill the
        extra space. Returns how many bytes have been read, 0 on EOF or
        undef> on eror, just like "sysread".

        This function is useful to implement many protocols where you read
        some data, see if it is enough to decode, and if not, read some
        more, where the naive or easy way of doing this would result in bad
        performance.

    nread = read_all fh, scalar, length
        Tries to read "length" bytes into "scalar". Unlike "read" or
        "sysread", it will try to read more bytes if not all bytes could be
        read in one go (this is often called "xread" in C).

        Returns the total nunmber of bytes read (normally "length", unless
        an error or EOF occured), 0 on EOF and "undef" on errors.

    nwritten = write_all fh, scalar
        Like "readall", but for writes - the equivalent of the "xwrite"
        function often seen in C.

    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:	1.1
Committed:	Mon Mar 14 02:41:52 2022 UTC (2 years, 2 months ago) by root
Branch:	MAIN
Log Message:	* empty log message *
#	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			$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=64
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			nread = extend_read fh, scalar, addlen=64
119			Calls "extend scalar, addlen" to ensure some space is available,
120			then do the equivalent of "sysread" to the end, to try to fill the
121			extra space. Returns how many bytes have been read, 0 on EOF or
122			undef> on eror, just like "sysread".
123
124			This function is useful to implement many protocols where you read
125			some data, see if it is enough to decode, and if not, read some
126			more, where the naive or easy way of doing this would result in bad
127			performance.
128
129			nread = read_all fh, scalar, length
130			Tries to read "length" bytes into "scalar". Unlike "read" or
131			"sysread", it will try to read more bytes if not all bytes could be
132			read in one go (this is often called "xread" in C).
133
134			Returns the total nunmber of bytes read (normally "length", unless
135			an error or EOF occured), 0 on EOF and "undef" on errors.
136
137			nwritten = write_all fh, scalar
138			Like "readall", but for writes - the equivalent of the "xwrite"
139			function often seen in C.
140
141			refcnt scalar[, newrefcnt]
142			Returns the current reference count of the given scalar and
143			optionally sets it to the given reference count.
144
145			refcnt_inc scalar
146			Increments the reference count of the given scalar inplace.
147
148			refcnt_dec scalar
149			Decrements the reference count of the given scalar inplace. Use
150			"weaken" instead if you understand what this function is fore.
151			Better yet: don't use this module in this case.
152
153			refcnt_rv scalar[, newrefcnt]
154			Works like "refcnt", but dereferences the given reference first.
155			This is useful to find the reference count of arrays or hashes,
156			which cannot be passed directly. Remember that taking a reference of
157			some object increases it's reference count, so the reference count
158			used by the *_rv-functions tend to be one higher.
159
160			refcnt_inc_rv scalar
161			Works like "refcnt_inc", but dereferences the given reference first.
162
163			refcnt_dec_rv scalar
164			Works like "refcnt_dec", but dereferences the given reference first.
165
166			ok scalar
167			uok scalar
168			rok scalar
169			pok scalar
170			nok scalar
171			niok scalar
172			Calls SvOK, SvUOK, SvROK, SvPOK, SvNOK or SvNIOK on the given
173			scalar, respectively.
174
175			CANDIDATES FOR FUTURE RELEASES
176			The following API functions (perlapi) are considered for future
177			inclusion in this module If you want them, write me.
178
179			sv_upgrade
180			sv_pvn_force
181			sv_pvutf8n_force
182			the sv2xx family
183
184			AUTHOR
185			Marc Lehmann <schmorp@schmorp.de>
186			http://home.schmorp.de/
187