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.
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