Hi Joe, On 19 November 2011 13:28, Joe Batt <joeb...@hotmail.co.uk> wrote:
> I am new to programming and on a very steep curve. I am using Python 3 to > learn and I am having trouble understanding exactly what pickling is. > I have written a program that asks for a URL and then writes the source > code from the URL to a file, then pickles the file I just created. > I am not sure why I pickle something as opposed to just saving it as a > normal file? > Pickling is a way for you to write arbitrary Python objects (or object structures) to file without having to think about their structure when writing (and read them back as well obviously). In general programming terms this is often referred to as serializing and deserializing. Anyway, it follows then that if you're handling the writing of data to a file yourself, such as when you're directly downling the textual content of a web page and writing that directly to a simple text file "by hand", that pickling is redundant/not relevant to your intent. So, either you write and read the text yourself, or (for example) you put the web page data into a list and then pickle (or unpickle) the list object to/from a file using Python's pickling support. Aside: If (as I'm suspecting) you're busy with puzzle 5 on the Python challenge, then I'll given you this hint: IIRC, there's a pickle file that can be downloaded from the Python challenge website, hidden somewhere in the puzzle 5 page (referenced in it directly or indirectly) that you're supposed to be interrogating in order to solve the puzzle. You're not supposed to be doing any pickling of the base web page of puzzle 5 at all. You *are* supposed to get the pickle data from the site, get it loaded up into Python (e.g. make it back into a Python object) and then figure out what it contains. Hope that helps, Walter
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