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As you are building code in Python, you may occasionally make a typo, or

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misplace a punctuation mark or forget a comma or something like that.

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The Python interpreter will do its best to try to guide you to where the errors

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are and sometimes it's helpful and sometimes it's not.

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Let's take a look at some examples here.

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There is a file in your debugging folder called saytime-errors.py. We will

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go ahead and make a working copy of this and we will call this

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saytime-errors-working.py.

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I will go ahead and open that working copy and this is the saytime module and it

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has some errors in it.

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So we will go ahead and we will run it and see what happens, and it's flagged

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a syntax error here.

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It says Syntaxerror:

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invalid syntax and you see that little caret is pointing at the second

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quote mark on line 26.

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So, we will scroll down here to line 26 and you see a little red x there and if

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I hold my cursor over the red x, we are getting a different error message and

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this is because Eclipse is doing its best to help too.

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So Eclipse is looking at it from the perspective of syntax highlighting and

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Python is actually trying to run the code.

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So, looking at it from two different perspectives they are going to give you two

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different perspectives.

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You know they both might be helpful and they might not.

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We are going to focus on the Python error messages here, because you are not

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always going to be coding inside of Eclipse, and the syntax highlighting

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parser is not always going to be as helpful as the parser that's trying to run the code.

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So, in this case, it's pointing at this character here.

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So, let's see if we can get the entire statement here on the screen and it

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starts here with _words = and it's got the opening curly brace and that ends

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down here with this closing curly brace.

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So the curly braces mean that this is a dictionary definition and you see

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there is our first key and a colon and there is a tuple object as the value and a comma.

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So, what we have here is a dictionary definition and we looked down here at this

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line with the error on it and we see there is colon there and there is the quote

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and there is the opening quote.

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It's not really obvious that there is anything wrong with it.

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That quote does not look like a problem.

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Even though the syntax error is pointing at that quote, that quote does not

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look like a problem.

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So let's look at it in order. Let's go through the process of looking at this

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whole definition and see if we can figure out what's wrong.

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So this is the first key and then there is colon. The value is that whole tuple

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object and then there is a comma and then there is another key and a colon and

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then the value, which is another tuple object, and a comma.

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So, we are seeing a pattern here.

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Key, value, comma, key, value, comma, we are getting closer, and here is a key

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and here is a value and there ought to be a comma there, because this looks like another key.

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So, we will put that comma in and we will save the file.

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We notice that the red x goes away.

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That's a good sign and we run it, and we get another error message.

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But this one is on line 70.

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So it looks like we have fixed this syntax error.

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You see the little red mark over here that's probably line 70, sure is, and we

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have a different error message.

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This one says, IndentationError:

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unindent does not match any outer indentation level.

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So it says it's an indentation error and we see we have another dictionary

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definition and all of that looks okay.

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You see a little red squiggly mark from the syntax highlighter.

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It's trying to help us there, but it's actually covering up the problem.

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You will notice that under those little red squiggly marks, there is an

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underscore and that underscore is indented farther out than the code above it,

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and so if we push that in one character and then save the file, see the red x goes away.

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Now we can see that underscore and we can see that indentation level.

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So that was an indentation error.

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You will notice that it's pointing at the wrong character here.

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If it was pointing back here, it might have been more obvious.

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That's typical of parsers everywhere.

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They will do their best to show you where the error is and more often than not,

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they are off by a few characters and sometimes even a few lines of code.

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So go ahead and run in it again and now we have another error, and this one says

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it's on line 118 or line 129.

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We have two errors being printed out here and what this is doing actually, we fill

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the screen with this, this is what's called a traceback in Python.

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It's telling where it encountered the error and it's tracing back its execution.

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So this is actually a runtime error.

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This is not syntax error.

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It says AttributeError, 'built_in_ function_or_method', object has no

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attribute 'tm_hour'.

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Here it is trying to assign this t.tm_ hour to a variable, self.hour, and that's at line 118.

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So, let's take a look at 118 and there is the line of code, and so what's

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happening is t here is an object that's getting passed into this constructor and saytime_t.

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So what's the line above this?

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Scroll back down here and a line above this is print saytime_t and this is at line 129.

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So let's go down to 129 and there it is. And so it's passing this time.local time

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and I happen to know that local time there is a function.

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It is not an attribute.

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So it's correct here, object has no attribute, ?_hour, and that's because we

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didn't call it with the function. The function has the attribute.

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So if we save this and run it again, now we get something else. This is not

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printed in red which means it's not being sent to standard error, which means

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it's not really a runtime error.

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This looks more like another kind of an error.

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It says bound method saytime.

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This is actually the output of this print statement here.

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It's printing a bound method, rather than running the bound method.

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So you see here .words.

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.words is supposed to be a method.

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It's actually a method in one of our classes here, there it is.

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See it's a method here, def words, and so what we need to do, see just like the one up here.

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It needs to have parenthesis.

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So we will save that and we will run it and our script works as we expected.

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So that's pretty much the process that you have to go through.

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If you type a whole bunch of code and it's not working the way that you expect

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it to work, you need to have some patience. You need to look at carefully and

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objectively and sometimes from myself, if I am not seeing and I will go and do

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something else, clear my head and come back and look at it.

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Usually at some point after I have cleared my head enough and I look at it

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enough, the errors will jump out and at me.

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These are the common type of syntax errors that you will run into in Python,

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things like forgetting parenthesis, indentation errors, forgetting commas, things like that.

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So you can start with looking for those sorts of things.

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Just have the patience, try and follow the code in your head, and eventually you

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ought to be able to find the errors and correct them.