Popular recipes by Trent Mick

subtract or add a month to a datetime.date or datetime.datetime (Python)

2010-06-25T18:41:19-07:00

Python recipe 577274 by Trent Mick (date, datetime, month).

Adding or subtracting a month to a Python datetime.date or datetime.datetime is a little bit of a pain. Here is the code I use for that. These functions return the same datetime type as given. They preserve time of day data (if that is at all important to you).

slugify: make a string usable in a URL or filename (JavaScript)

2011-07-12T17:46:49-07:00

JavaScript recipe 577787 by Trent Mick (filename, nodejs, slug, slugify, url). Revision 2.

"Slugify" a string so it has only alphanumeric and hyphen characters. Useful for URLs and filenames. This is a JavaScript (node.js too) version of Recipe 577257.

Note: It is missing the guarantee that only ascii characters are passed through. I don't know an NFKD equivalent in JavaScript-land.

Perl URL encode and decode (Perl)

2010-11-02T17:52:46-07:00

Perl recipe 577450 by Trent Mick (decode, encode, url).

URL encode and decode functions for Perl.

nicerest: pretty-print JSON output (JavaScript)

2011-01-18T22:59:12-08:00

JavaScript recipe 577549 by Trent Mick (curl, json, node, nodejs, rest). Revision 3.

Save this to "nicerest", chmod +x-it, and pipe your REST API curl calls through this for nicer output. It will notice HTTP headers (curl's -i option) and skips those before attempting to pretty-print the following JSON.

Note: This is currently using node 0.2. I should update for 0.3 changes (I think process.openStdin changed).

query yes/no (Python)

2010-03-09T17:57:28-08:00

Python recipe 577058 by Trent Mick (ask, cli, no, query, raw_input, yes). Revision 2.

Ask the user a question using raw_input() and looking something like this:

QUESTION [Y/n] 
...validate...

See also: Recipe 577096 (query custom answers), Recipe 577097 (query yes/no/quit), Recipe 577098 (query long), Recipe 577099 (query)

transform command line arguments to args and kwargs for a method call (Python)

2010-03-21T22:41:42-07:00

Python recipe 577122 by Trent Mick (argv, cli, json). Revision 2.

For many of my Python modules I find it convenient to provide a small if __name__ == "__main__": ... block to be able to call individual methods from the command line. This requires some kind of translation of command-line string arguments to args and kwargs for the method call. This recipe uses a few conventions to do that:

the first argument is the method name
positional args are positional (duh)
"key=value" is a keyword argument
an attempt is made to interpret arguments as JSON to allow specifying types other than string

slugify: make a string usable in a URL or filename (Python)

2010-06-07T04:11:55-07:00

Python recipe 577257 by Trent Mick (ascii, django, filename, slug, slugify, url). Revision 2.

"Slugify" a string so it is ascii, has only alphanumeric and hyphen characters. Useful for URLs and filenames. This is heavily based on the slugify in Django.

Note: presumes that you've import red higher up in your module.

quick 3-column grid CSS (CSS)

2010-09-15T17:13:26-07:00

CSS recipe 577391 by Trent Mick (column, grid, layout).

CSS snippet for a 3-column grid. Based on that used for some Apple product pages.

HTML:

<div class="grid3col">
  <div class="column first">
    ...
  </div>
  <div class="column">
    ...
  </div>
  <div class="column last">
    ...
  </div>
</div>

In general, you have to recalculate the widths based on (a) the available full width in your pages and (b) the amount a spacing you want between columns.

node.js quicklog method to log to a file (JavaScript)

2010-08-11T05:08:57-07:00

JavaScript recipe 577351 by Trent Mick (logging, nodejs).

I tend to have a "quicklog" method for a few of the languages I'm working in to do logging when stdout/stderr isn't necessarily available (GUI app) or convenient (lots of other output on stdout, etc.). My usage with nodejs was while working on the node REPL. Log output to stdout interfered with the REPL.

Using a getter for a one-time calculation of a JavaScript object attribute (JavaScript)

2010-07-16T18:10:51-07:00

JavaScript recipe 577310 by Trent Mick (getter, performance).

This is a technique for using a JavaScript getter to calculate the value of an attribute just the first time. Rather than caching the value in some private variable and returning it, you just delete the getter and put the calculated value in its place.

Note: I'd read about this technique ages ago, but forgot the details and had to look-up "delete" for removing the getter. :)

file path generator from path patterns (Python)

2010-07-09T19:10:59-07:00

Python recipe 577230 by Trent Mick (cli, files, path, paths, walk). Revision 4.

Provides a _paths_from_path_patterns that will generate a list of paths from a list of path patterns. A "path pattern" can include glob chars. By default it generates a recursive listing of file paths, but: recursion can be turned off, file and/or dir paths can be listed. It supports a list of glob exclusions or inclusions.

This function makes it easy to implement typical "-r|--recursive" and "-x|--exclude" options for command-line scripts that work on given file paths. See example usages below.

Note: I use a leading _ on function names because my typical usage of my recipes is as re-usable internal functions in Python modules.

Python script main line for graceful exception handling and logging (Python)

2010-09-11T05:46:59-07:00

Python recipe 577258 by Trent Mick (error, logging, main, mainline, script). Revision 5.

This is a recipe is often use for the mainline of my Python scripts. With this recipe your Python script will:

gracefully handle Ctrl+C (i.e. KeyboardInterrupt)
log an error (using the logging module) for uncaught exceptions, importantly with the file and line number in your Python code where the exception was raised
gracefully ignore a closed output pipe (common when the user pipes your script through less and terminates that)
if your script logger is enabled for DEBUG level logging, a full traceback will be shown for an uncaught exception

Presumptions:

you have a global log variable a la:

import logging
log = logging.setLevel("scriptname")

your script's entry point is a function def main(argv): ...

parse a date/time string to a `datetime` instance (Python)

2010-04-02T07:32:17-07:00

Python recipe 577135 by Trent Mick (date, datetime, parse, time). Revision 2.

>>> import datetime
>>> str(datetime.datetime.now())
'2010-03-21 21:33:32.750246'
>>> str(datetime.date.today())
'2010-03-21'

This function goes the other way for date and datetime strings of this format.

query yes/no/quit (Python)

2010-03-09T17:57:18-08:00

Python recipe 577097 by Trent Mick (ask, cli, no, query, quit, raw_input, yes).

Ask the user a question using raw_input() and looking something like this:

QUESTION [Y/n/q] 
...validate...

See also: Recipe 577058 (query yes/no), Recipe 577096 (query custom answers), Recipe 577098 (query long), Recipe 577099 (query)

command line query (Python)

2010-03-09T18:37:52-08:00

Python recipe 577098 by Trent Mick (ask, cli, query, raw_input). Revision 3.

Ask the user a question using raw_input() and looking something like this (style=="compact"):

QUESTION [DEFAULT]: _
...validation...

or this (style=="verbose"):

QUESTION
Hit <Enter> to use the default, DEFAULT.
> _
...validate...

It supports some basic validation/normalization of the given answer.

See also: Recipe 577058 (query yes/no), Recipe 577097 (query yes/no/quit), Recipe 577096 (query custom answers)

query custom answers (Python)

2010-03-09T17:57:22-08:00

Python recipe 577096 by Trent Mick (cli, query).

Ask the user a question using raw_input() and looking something like this:

Frob nots the zids? [Yes (default), No, quit] _
...validate...

See also: Recipe 577058 (query yes/no), Recipe 577097 (query yes/no/quit), Recipe 577098 (query long), Recipe 577099 (query)

query (Python)

2010-03-09T18:34:05-08:00

Python recipe 577099 by Trent Mick (ask, cli, query, raw_input).

Ask/prompt the user for a short piece of data. Recipe 577098 is a much more generic/functional (but longer) take on this.

write_path and load_path methods for file generation scripts (Python)

2010-07-27T06:45:51-07:00

Python recipe 577172 by Trent Mick (files). Revision 7.

I have a lot of scripts that end up writing files (often build system stuff). Everytime I either end up writing the obvious quick content = open(path).read() or I re-implement a function that handles things like: making a backup, some typical logging, encoding support, trying to make it no-op if no changes, etc.

In this recipe I'll try to add a number of these features so I don't have to keep re-writing this. :) So far this is just a start.

Current features:

rudimentary encoding support
logging on a given log argument
create_backup argument to create a backup file
writes to a temporary file and uses atomic os.rename to avoid destroying the existing file if writing fails

send a multipart email (Python)

2009-10-15T13:56:10-07:00

Python recipe 576931 by Trent Mick (email, multipart, smtp). Revision 2.

A simple function to send an email (can specify text and html parts).

See also: Recipe 576824 (send via Gmail's SMTP server), Recipe 576858 (more complex, but supports attachments).

touch (Python)

2009-09-28T16:19:23-07:00

Python recipe 576915 by Trent Mick (file, shell, touch, unix).

Python function a la the Unix touch program (man touch).