=head1 NAME Convert::Scalar - convert between different representations of perl scalars =head1 SYNOPSIS use Convert::Scalar; =head1 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. =over 4 =cut package Convert::Scalar; BEGIN { $VERSION = 1.12; @ISA = qw(Exporter); @EXPORT_OK = qw(readonly readonly_on readonly_off weaken unmagic len grow extend extend_read readall writeall); %EXPORT_TAGS = ( taint => [qw(taint untaint tainted)], utf8 => [qw(utf8 utf8_on utf8_off utf8_valid utf8_upgrade utf8_downgrade utf8_encode utf8_decode utf8_length)], refcnt => [qw(refcnt refcnt_inc refcnt_dec refcnt_rv refcnt_inc_rv refcnt_dec_rv)], ok => [qw(ok uok rok pok nok niok)], ); require Exporter; Exporter::export_ok_tags(keys %EXPORT_TAGS); require XSLoader; XSLoader::load Convert::Scalar, $VERSION; } =item 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. =item utf8_on scalar Similar to C, but additionally returns the scalar (the argument is still modified in-place). =item utf8_off scalar Similar to C, but additionally returns the scalar (the argument is still modified in-place). =item 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). =item utf8_upgrade scalar Convert the string content of the scalar in-place to its UTF8-encoded form (and also returns it). =item 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 C is not true (the default), croaks. =item utf8_encode scalar Convert the string value of the scalar to UTF8-encoded, but then turn off the C flag so that it looks like bytes to perl again. (Might be removed in future versions). =item utf8_length scalar Returns the number of characters in the string, counting wide UTF8 characters as a single character, independent of whether the scalar is marked as containing bytes or mulitbyte characters. =item $old = readonly scalar[, $new] Returns whether the scalar is currently readonly, and sets or clears the readonly status if a new status is given. =item readonly_on scalar Sets the readonly flag on the scalar. =item readonly_off scalar Clears the readonly flag on the scalar. =item unmagic scalar, type Remove the specified magic from the scalar (DANGEROUS!). =item weaken scalar Weaken a reference. (See also L). =item taint scalar Taint the scalar. =item tainted scalar returns true when the scalar is tainted, false otherwise. =item untaint scalar Remove the tainted flag from the specified scalar. =item length = len scalar Returns SvLEN (scalar), that is, the actual number of bytes allocated to the string value, or C, is the scalar has no string value. =item 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). =item 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 C, 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. =item nread = extend_read fh, scalar, addlen=64 Calls C to ensure some space is available, then do the equivalent of C to the end, to try to fill the extra space. Returns how many bytes have been read, C<0> on EOF or undef> on error, just like C. 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. =item nread = read_all fh, scalar, length Tries to read C bytes into C. Unlike C or C, it will try to read more bytes if not all bytes could be read in one go (this is often called C in C). Returns the total nunmber of bytes read (normally C, unless an error or EOF occurred), C<0> on EOF and C on errors. =item nwritten = write_all fh, scalar Like C, but for writes - the equivalent of the C function often seen in C. =item refcnt scalar[, newrefcnt] Returns the current reference count of the given scalar and optionally sets it to the given reference count. =item refcnt_inc scalar Increments the reference count of the given scalar inplace. =item refcnt_dec scalar Decrements the reference count of the given scalar inplace. Use C instead if you understand what this function is fore. Better yet: don't use this module in this case. =item refcnt_rv scalar[, newrefcnt] Works like C, 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 C<*_rv>-functions tend to be one higher. =item refcnt_inc_rv scalar Works like C, but dereferences the given reference first. =item refcnt_dec_rv scalar Works like C, but dereferences the given reference first. =item ok scalar =item uok scalar =item rok scalar =item pok scalar =item nok scalar =item niok scalar Calls SvOK, SvUOK, SvROK, SvPOK, SvNOK or SvNIOK on the given scalar, respectively. =back =head2 CANDIDATES FOR FUTURE RELEASES The following API functions (L) 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 =head1 AUTHOR Marc Lehmann http://home.schmorp.de/ =cut 1