Python syntax errors

Question

I am having a few problems with my code.. I am following an example in the book "Beginning Game Development with Python and Pygame" (example 2-4 and 2-5) and I am getting syntax errors. Below is the code in question. I am new to Python and probably just did a typo.

The book uses python 2.4. I'm getting the error for 2.7 and 3.2.

Two problems:

the code line with:

my_tank = Tank("Bob")

is receiving a syntax error. my_tank is highlighted. I did get it to start working but I am not sure why it started to.

The code line with:

print self.name, "fires on", enemy.name

is also recieveing a syntax error. The self in this line is highlighted. When my_tank stared working I started to receive this error. Not sure whats going on here.

class Tank(object):

    def _init_(self, name):
        self.name = name
        self.alive = True
        self.ammo = 5
        self.armor = 60

    my_tank = Tank("Bob")

    def _str_(self):

        if self.alive:
            return "%s (%i armor, %i shells)" % (self.name, self.armor, self.ammo)
        else:
            return "%s (dead)" % self.name

    def fire_at(self, enemy):

        if self.ammo >= 1:
            self.ammo -= 1
            print self.name, "fires on", enemy.name
            enem.hit()
        else:
            print self.name, "has no shells!"

    def hit(self):

        self.armor -= 20
        print self.name, "is hit!"
        if self.armor <= 0:
            self.explode()

    def explode(self):

        self.alive = False
        print self.name, "explodes!"

Post the actual error you receive, including the entire traceback. Also, it is important that you specify what Python version you're using, since their syntax differs (for instance in how print is used). Do you get these errors with Python 2.7 or Python 3.2 or both? — BrenBarn
– BrenBarn, Commented Aug 6, 2012 at 3:04
A quick guess: you have _init_ and _str_ in your code, while the correct names for default methods are __init__ and __str__ (notice two underscores) — aland
– aland, Commented Aug 6, 2012 at 3:07
@aland: You're right, but that shouldn't produce a SyntaxError. — Mechanical snail
– Mechanical snail, Commented Aug 6, 2012 at 3:08
@LewisBellinger: Running in Python 2.7, that line gives a NameError, not a syntax error. — Mechanical snail
– Mechanical snail, Commented Aug 6, 2012 at 3:10

chrisaycock · Accepted Answer · 2012-08-06 03:07:21Z

4

As @aland notes, the function names are supposed to be __init__ and __str__.

Also, this line should be outside the class:

my_tank = Tank("Bob")

After all, you want an instance of the class for later use.

answered Aug 6, 2012 at 3:07

chrisaycock

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3 Comments

Bill Lynch Over a year ago

From a quick glance, you could also mention enem.hit() which should probably be enemy.hit().

chrisaycock Over a year ago

@sharth Hmm, he didn't mention a compiler error for that line in the question. Good catch!

Lewis Bellinger Over a year ago

Yes i didnt notice that i need two underscores under init and str and then moved my my_tank line to outside of the class.... the book didnt mention to do that... or i overlooked it? :p Thx for the help and i recieve no errors... sweet

Community · Accepted Answer · 2017-05-23 12:04:43Z

2

chrsaycock's answer looks correct, but I want to emphasize how important it is to pay attention to the traceback you receive.

When I run your code I get this error:

Traceback (most recent call last):
  File "<pyshell#86>", line 1, in <module>
    class Tank(object):
  File "<pyshell#86>", line 9, in Tank
    my_tank = Tank("Bob")
NameError: name 'Tank' is not defined

Your question should have been something along the lines of "Why am i getting a NameError here? I've defined Tank in line one."

Don't think of this error as a generic syntax error. The type of the error tells you much of what you need to know.

edited May 23, 2017 at 12:04

CommunityBot

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answered Aug 6, 2012 at 3:24

Steven Rumbalski

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1 Comment

Lewis Bellinger Over a year ago

Yes i didnt notice that i need two underscores under init and str and then moved my my_tank line to outside of the class.... the book didnt mention to do that... or i overlooked it? :p Thx for the help and i recieve no errors... sweet

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