The.Failboat.me » Programming

Rocket: A Lua Sqlite3 ORM manager

Lee — Mon, 26 Jul 2010 04:44:44 +0000

Relational databases are designed so that they can both store and describe data. Most programming level APIs do wonderful jobs of maintaining the former aspect. I mean, what ORM doesn’t automatically map the insert method to the so very generic…

See.lua – Documentation

Lee — Sun, 25 Jul 2010 04:56:36 +0000

See.lua – A Lua introspection library

	> see(string)

	.byte(?)            .char(?)            .dump(?)            .find(?)
	.format(?)          .gfind(?)           .gmatch(?)          .gsub(?)
	.join(self, table, ...)                 .len(?)
	.lower(?)           .match(?)           .rep(?)             .reverse(?)
	.sub(?)             .upper(?)

Lua is a wonderful little language that lets you do…

see.lua – Introspecting Lua objects

Lee — Fri, 23 Jul 2010 02:53:01 +0000

As via its python equivalent, see.lua takes in an object and prints out a list of its elements as well as metatable methods in readable text.

> require "see"

> s = see(string)
.byte(?)            .char(?)            .dump(?)            .find(?)

…

Pydev: The Best Python IDE

Lee — Thu, 22 Jul 2010 03:09:15 +0000

While I don’t usually advertise, I love eclipse for all of its feature rich implementations of language specific IDE’s. Among those is Pydev, a complete first class IDE for Python.
Recently, Pydev just hit version 1.6.0 (Congratulations!) with the…

Python: Self references in List comprehension

Lee — Wed, 21 Jul 2010 03:09:23 +0000

One of the great abilities in Python that is copied over from Haskell is the ability to construct lists from other lists or iterators inline. This is of course limiting in certain cases where self references are necessary. For example,…

strcpy() implementation in C/C++

Lee — Mon, 19 Jul 2010 23:51:09 +0000

One of our ubiquitous C functions can be rather easily recreated via C:

char* strcpy(char* other, char* self){
    while (*self) *other++=*self++;
    *other = '\0';
}

Note that C strings are null terminating, hence we create a…

Python Tip: Copying an object

Lee — Mon, 19 Jul 2010 02:30:46 +0000

One of the several “features” of python that often land beginners head over feet with their faces in the mud is the distinction between references and copies. Say we have the following list a:

a = [1,3,5,7,9,11]

…

Brain Teaser: Multiply by 6

Lee — Sat, 17 Jul 2010 07:22:21 +0000

How do I go about multiplying a real number n by 6 in python without using the * or the + operators?

Solution:

x6 = lambda n: (n<<3) - n - n

Rationale:

Tips and Tricks for Lua Beginners: Writing an at.exit registry

Lee — Fri, 16 Jul 2010 18:24:36 +0000

It’s relatively simple to write a function that takes in a function and executes it once Lua terminates.

at = {}
function at.exit(fn)
     getmetatable(newproxy(true)).__gc = fn
end

The caveat for at.exit() is that on…

Lua – Get a table of function arguments

Lee — Fri, 16 Jul 2010 18:04:51 +0000

The lua standard libraries do not provide anything that helps you get the table of arguments for a given function. This can be accomplished by directly introspecting the bytecode of the function. The following snippet generates a function get_args that…

Lua – Get number of parameters in a function

Lee — Thu, 15 Jul 2010 16:04:22 +0000

The following snippet defines a function num_args(func) that returns the number of parameters within a function as a string:

num_args(function(a,b,c) end) --> 3

It also works with functions that have variable arguments:

num_args(function(a,...)

…

Serializing Lua objects into Lua Code

Lee — Wed, 14 Jul 2010 04:00:08 +0000

The following little snippet allows you to ‘pickle’ Lua objects directly into Lua code (with the exception of functions, which are serialized as raw bytecode). Metatable support is on the way, but for now, it should be useful enough.

Example…

Lua Exception Handling

Lee — Sat, 10 Apr 2010 02:11:26 +0000

Wouldn’t it be awsome if you could do something like

dofile "try"

try{
	function()
		a = a/a
	end
}.except(Exceptions.ValueError){
	function(_, exceptions, detail)
		print(detail)
	end
}

And get

lua:5: attempt to perform arithmetic on

…

Linked Lists via ctypes in Python

Lee — Wed, 07 Apr 2010 04:00:22 +0000

from ctypes import *

class linknode(Structure):
    pass
linknode._fields_ = [
                ("nextNode", POINTER(linknode)),
                ("intData", c_int),
                ]
class linked_list():
    head_node = None
    def add(self, int_data):
        node_to_add = linknode(intData = c_int(int_data))
        if (self.head_node == None):
            self.head_node = node_to_add
        else:
            traverse_node

…

Context aware Lua Macros

Lee — Fri, 19 Feb 2010 01:06:43 +0000

Will automatically detect locals as well as global variables.

Usage: Macro “text ${Lua Code} more text”

test = Macro "Hello ${jack} ${'Bauer'}"

function test1()
	local jack = "Jack"
	print(test)
end

test1()

function test2()
	local jack = "No

…