Free variable names software for linux

Variable::Alias is a Perl module created to alias any variable to any other variable.

SYNOPSIS

use Variable::Alias alias;
my $src;
my $a;
our $b;
my @c;
our @d;

alias $src => $a;
alias $a => $b;
alias $b => $c[0];
alias @c => @d;

$src=src;
# All the other variables now have the string
# src in the appropriate places.

There are various ways to alias one variable to another in Perl. The most popular is by assigning to typeglobs. This is quite efective, but only works with globals. Another method is to use a module like Lexical::Alias or Devel::LexAlias, but as their names suggest, these only work with lexicals. Theres no way to alias an element of an array or hash.

Variable::Alias changes all that. It uses a tie to provide One True Way to alias a variable.

Interface

Variable::Alias may export any or all of five functions. If youve used Lexical::Alias, the interface is virtually identical.

alias(VAR, VAR)

alias takes two variables of any type (scalar, array or hash) and aliases them. Make sure they have the sigil you want on the front.

This function is only available in Perl 5.8.0 and later, because the prototype tricks it uses were first implemented in that version.

alias_s(SCALAR, SCALAR)

alias_s takes two scalars and aliases them.

alias_a(ARRAY, ARRAY)

alias_a takes two arrays and aliases them. Note that this is actual arrays, not array elements, although you can alias references in elements, like so:

alias_a(@short, @{$some->sequence->{of}->calls->{thats}[2]{long}});

alias_h(HASH, HASH)

alias_h takes two hashes and aliases them.

alias_r(REF, REF)

alias_r takes two references and aliases them. The referents must be of the same type.

Twisted Names project is both a domain name server as well as a client resolver library.
Twisted Names comes with an "out of the box" nameserver which can read most BIND-syntax zone files as well as a simple Python-based configuration format.
Twisted Names can act as an authoritative server, perform zone transfers from a master to act as a secondary, act as a caching nameserver, or any combination of these.
Twisted Names client resolver library provides functions to query for all commonly used record types as well as a replacement for the blocking gethostbyname() function provided by the Python stdlib socket module.
Twisted Names is available under the MIT Free Software licence.
Enhancements:
- Errors in the markup used in API documentation have been fixed.
- A bug where the DNS client would sometimes drop a response has been fixed.
- A bug which prevented non-IN lookups from generating malformed queries has been fixed.

Variable::Strongly::Typed is a Perl module to let some variables be strongly typed.

SYNOPSIS

use Variable::Strongly::Typed;
my $int :TYPE(int); # must have an int value
my $float :TYPE(float); # must have a float value
my $string :TYPE(string); # must not be a reference
my $file :TYPE(IO::File); # must be an IO::File
my @array_of_ints :TYPE(int); # Each slot must contain
# an int
my %hash_of_floats :TYPE(float); # Each value must be a float

my $int_own_error :TYPE(int, &my_own_error_handler);
# Roll my own error handler

my @array_of_rgb :TYPE(&red_green_blue); # my enumerated type

# For subs!!
sub return_an_int :TYPE(int) {
# .. do some stuff ..
return $something;
}

# ... and later ...

$int = 23; # All is well
$int = howdy!; # This line will croak with a good error message

$float = 3.23; # All is well, nothing to see here
$float = new XML::Parser; # croak!

$array_of_ints[23] = 44; # Groovy
$array_of_ints[12] = yah; # croak!

$hash_of_floats{pi} = 3.14159; # no problem
$hash_of_floats{e} = new IO::File; # croak!

# Return 1 if this val is RED, BLUE, or GREEN
# 0 otherwise
sub red_green_blue {
local $_ = shift;

/A RED z/xms || /A BLUE z/xms || /A GREEN z/xms;
}

$array_of_my_very_own_types[23] = 99; # croak!
$array_of_my_very_own_types[2] = BLUE; # OK!

$int_own_error = lksdklwe; # The sub my_own_error_hanlder
# will be # called with the
# offending value

my $got_it = return_an_int(); # Will croak (or call your error
# function) # if this sub doesnt
# return an int

This modules allow you to strongly type your variables. Also known as the no fun module - it can greatly enhance you codes quality and robustness.

By enforcing types on some (or all) of your variables you will eliminate a large class of careless (& not so careless) errors.

This could also aid an editor or code-browsing tools to verify code correctness without having to execute the script.

MySQL Global User Variables UDF is a MySQL extension to store persistent variables.

This shared library adds simple user functions to MySQL in order to keep persistent shared variables in memory. These variables and their values are available to all clients. Any data can be stored into these persistent variables, including BLOBs. Since updates are atomic and way faster than MEMORY tables, this is an easy and efficient way to handle counters and sequences.

Usage:

Storing a value

An unlimited number of user variables can be created, as long as memory is available.
The GLOBAL_STORE(, ) stores a new shared global variable.

Examples:

mysql> DO GLOBAL_STORE("online_users", 42);
mysql> DO GLOBAL_STORE("secret_key", "pajfUyfnd");

The GLOBAL_STORE() function always returns 1 unless an error occurred.

Fetching a value

Reading the value of a variable is the job of the GLOBAL_GET() function.
The value is returned, or NULL is the variable is undefined.

Example:

mysql> SELECT GLOBAL_GET("online_users;);
42

mysql> SELECT id FROM pxs WHERE secret_key = GLOBAL_GET("secret_key");
1

Atomic increments

A single function call can read the previous value, add an integer (that can be negative), and store the new value into the variable.

The function is GLOBAL_ADD(, ) and the return value is the new value of the variable.
Updates are always atomic, if the old value is 18 and you add 1, you will always get back 19.

Example:

mysql> DO GLOBAL_ADD("online_users", 1);
mysql> SELECT GLOBAL_ADD("online_users", -4);
39

If the value of a variable was a string, the new value is the increment:

mysql> SELECT GLOBAL_ADD("secret_key", 12);
12

Adding a value to an undefined variable returns NULL.
A handy variant is GLOBAL_ADDP(, ). GLOBAL_ADDP() is similar to GLOBAL_ADD() but returns the PREVIOUS value of the variable instead of the new one.

Example:

mysql> DO GLOBAL_SET("xxx", 10);
mysql> SELECT GLOBAL_ADDP("xxx", 1);
10
mysql> SELECT GLOBAL_ADDP("xxx", 1);
11

Installation:

On most systems, compiling and installing the library should be as simple as typing (as root):

make install

The shared library is installed as /usr/local/lib/udf_global_user_variables.so

If the base directory of your MySQL installation is not in /usr/local, just type:

make

and then copy udf_global_user_variables.so to the right location for UDFs on your system (maybe /usr/lib/).

The name of a variable is limited to 256 bytes. If that limit is too low for your specific application, just edit the MAX_NAME_LENGTH variable on top of the .c file and reinstall. Variable names can contain binary characters.

Values are limited to 65536 bytes. If that limit is too low for you, edit the MAX_VALUE_LENGTH variable and reinstall.

Variable::Strongly::Typed::Array is a Perl module for strongly typed array.

SYNOPSIS

This class is utilized by Variable::Strongly::Typed - you dont access this directly

my @array_of_ints :TYPE(int); # Each slot must contain an int
my @array_of_rgb :TYPE(&red_green_blue); # my enumerated type

# ... and later ...

$array_of_ints[23] = 44; # Groovy
$array_of_ints[12] = yah; # croak!

# Return 1 if this val is RED, BLUE, or GREEN
# 0 otherwise
sub red_green_blue {
local $_ = shift;

/A RED z/xms || /A BLUE z/xms || /A GREEN z/xms;
}

$array_of_my_very_own_types[23] = 99; # croak!
$array_of_my_very_own_types[2] = BLUE; # OK!

Variable::Strongly::Typed::Scalar is Perl module for strongly typed scalar.

SYNOPSIS

This class is utilized by Variable::Strongly::Typed - you dont access this directly
=head1 DESCRIPTION

Persistent::Oracle is a persistent class implemented using an Oracle database.

SYNOPSIS

use Persistent::Oracle;
use English; # import readable variable names like $EVAL_ERROR

eval { ### in case an exception is thrown ###

### allocate a persistent object ###
my $emp = new Persistent::Oracle(dbi:Oracle:ORCL,
scott, tiger, emp);

### define attributes of the object ###
$emp->add_attribute(empno, ID, Number, undef, 4);
$emp->add_attribute(ename, Persistent, VarChar, undef, 10);
$emp->add_attribute(job, Persistent, VarChar, undef, 9);
$emp->add_attribute(mgr, Persistent, Number, undef, 4);
$emp->add_attribute(hiredate, Persistent, DateTime, undef);
$emp->add_attribute(sal, Persistent, Number, undef, 7, 2);
$emp->add_attribute(comm, Persistent, Number, undef, 7, 2);
$emp->add_attribute(deptno, Persistent, Number, undef, 2);

### query the datastore for some objects ###
$emp->restore_where(qq{
sal > 1000 and
job = CLERK and
ename LIKE M%
}, "sal, ename");
while ($emp->restore_next()) {
printf "ename = %s, emp# = %s, sal = %s, hiredate = %sn",
$emp->ename, $emp->empno, $emp->sal, $emp->hiredate;
}
};

if ($EVAL_ERROR) { ### catch those exceptions! ###
print "An error occurred: $EVAL_ERRORn";
}

ABSTRACT

This is a Persistent class that uses an Oracle database table to store and retrieve objects. This class can be instantiated directly or subclassed. The methods described below are unique to this class, and all other methods that are provided by this class are documented in the Persistent documentation. The Persistent documentation has a very thorough introduction to using the Persistent framework of classes.

Libeval provides simple means of evaluating simple arithmetic expressions involving literal numeric values, variables and functions using the addition (+), subtraction (-), multiplication (*), division (/), modulo division (), exponentiation (^), sign (+-), percentag (%) and grouping (()) operators.
Libeval provides a means of setting and interrogating variables, defining functions and converting error codes into human readable strings. A number of predefined functions are included with libeval that wrap the existing standard C library math functions.
You can evaluate an expression by calling the eval() function. eval() takes two parameters, the expression to evaluate (as a simple C string) and a reference to a double precision float in which to put the result. If eval() encounters an error it returns a non-zero value, otherwise, if everything went well, it returns zero.
The error code returned by eval() can be converted into a human readable string by the eval_error() function. eval_error() takes one parameter, the error code returned by eval(),and returns a constant string describing the error.
Variables can be manipulated with the eval_set_var() and eval_get_var() functions.
eval_set_var() sets the named variable to the specified double precision value. eval_set_var() takes two parameters, the name of the variable to set as a simple C string, and the double precision float value to set the variable to. it returns 0 (zero) on success, non-zero on failure.
eval_get_var() gets the value of the named variable. eval_get_var() takes two parameters, the name of the variable as a simple C string and a reference to a double precision float in which to store the variables value. it returns 0 (zero) on success, non-zero on failure.
Functions can be defined with the eval_def_fn() function, which takes the name of the function as a simple C string, a pointer to a C function implementing the function, a pointer to a block of custom storage for use by the function and the number of arguments taken by the function. The prototype for the implementation function is:
int fn(int args, double *arg, double *rv, void *data);
The first two parameters (args and arg) are similar to the standard parameters to the main() function in C, the args parameter indicates how many elements are the argument list, and arg is the argument list itself. The third parameter (rv) is the return value from the function. The last parameter (data) is the custome storage block passed in when the function was defined.
If you specify a positive value (including zero) as the number of arguments for a function, libeval will only all the function to be called with exactly that number of parameters. If you specify a -1 (negative one) for the number of arguments, the function can be called with any number of parameters.
The following functions are predefined:
abs(x) absolute value of x
int(x) integer part of x
round(x) round x to nearest integer
trunc(x) truncate x (same as int(x))
floor(x) round x to nearest lesser integer
ceil(x) round x to nearest greater integer
sin(x) sine of x (radians)
cos(x) cosine of x (radians)
tan(x) tangent of x (radians)
asin(x) arc sine of x (radians)
acos(x) arc cosine of x (radians)
atan(x) arc tangent of x (radians)
sinh(x) hyperbolic sine of x (radians)
cosh(x) hyperbolic cosine of x (radians)
tanh(x) hyperbolic tangent of x (radians)
asinh(x) hyperbolic arc sine of x (radians)
acosh(x) hyperbolic arc cosine of x (radians)
atanh(x) hyperbolic arc tangent of x (radians)
deg(x) convert radians to degrees
rad(x) convert degrees to radians
ln(x) natural logarithm of x
log(x) base 10 logarithm of x
sqrt(x) square root of x
exp(x) e to x power
rand() random number between 0.0 and 1.0
fact(x) factorial of x (or gamma(x) if x is non-integer)
sum(...) sum of the arguments
min(...) minimum value in arguments
max(...) maximum value in arguments
avg(...) average of arguments
med(...) median of arguments
var(...) variance of arguments
std(...) standard deviation of arguments
Finally, you can get a set of bookkeepping information about the eval_expr libray with the eval_info() function. eval_info() takes nine parmaeters: three references to integer values for the version, revision and build numbers of the current eval_expr library, and three pairs of buffer address and buffer size limit for authors name, copyright info and license info.
You can use libeval by including the libeval header in your program source
#include
and then by linking your program against the libeval library
gcc -o myprog myprog.c -leval
Enhancements:
- A bug in the var() function and version string construction were fixed.