Python Jumpstart by Building 10 Apps Transcripts
Chapter: App 8: File Searcher App
Lecture: Introduction to the File Searcher App

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0:00 Hello and welcome to app number 8.
0:02 This is a file searching app, and it's going to be able to search for text
0:06 within files across a massive quantity and number of files.
0:11 So, let's see exactly how this is going to work.
0:14 What are we going to build- well, it's going to look like this,
0:17 header, as always, and then it's going to ask the user
0:20 what directory do you want to start searching in
0:23 and we'll search recursively through that entire tree that subdirectory sort of thing,
0:27 and what text, what string you want to look for.
0:29 Here we are looking in our previous app for the word dragon,
0:33 and here you can see we've found two matches,
0:35 in the file on line 7 you can see we are defining
0:39 a class called dragon that is derived from creature,
0:42 so there the word dragon appeared.
0:44 And then, in the on line 24,
0:46 we found where we were using the name space from the other module
0:49 to actually allocate or initialize a dragon and this is what a dragon with level 50-
0:54 Now we just say that's it, total number matches was two, we are done.
0:59 You might think that this app is largely about files.
1:02 But it's not, we've spent a lot of time on working with directories and files and so on,
1:06 we will have to do that, yes, but that's not the primary focus,
1:09 what we are going to look at is actually how do we use this concept
1:13 of a generator method which is implemented with the yield and yield from keywords,
1:18 along with recursion to put together a pipeline of processing,
1:22 a chain of what are called generator methods that are extremely efficient
1:26 at processing large quantities of data
1:29 so you'll see that we are using this app
1:31 to actually search through like 2.5 gigs of text files,
1:36 the memory usage is almost 0 above just standard,
1:40 hey what's your name sort of input type of app
1:43 and the key to making this work is the yield keyword and the generator methods.
1:48 We are going to talk about path operations
1:50 and very basic string searching
1:52 but we are going to focus on this concept of a processing pipeline
1:55 and we just happen to use files directories and text as our input.