# Dive Into Python

Python for experienced programmers

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## Chapter 1. Getting To Know Python

## 1.1. Diving in

Here is a complete, working Python program.

It probably makes absolutely no sense to you. Don’t worry about that; we’re going to dissect it line by line. But read through it first and see what, if anything, you can make of it.

### Example 1.1. `odbchelper.py`

If you have not already done so, you can download this and other examples used in this book.

    def buildConnectionString(params):
        """Build a connection string from a dictionary of parameters.

        Returns string."""
        return ";".join(["%s=%s" % (k, v) for k, v in params.items()])

    if __name__ == "__main__":
        myParams = {"server":"mpilgrim", \
                    "database":"master", \
                    "uid":"sa", \
                    "pwd":"secret" \
                    }
        print buildConnectionString(myParams)

Now run this program and see what happens.

In the Python IDE on Windows, you can run a module with File->Run... (Ctrl-R). Output is displayed in the interactive window.

In the Python IDE on Mac OS, you can run a module with Python->Run window... (Cmd-R), but there is an important option you must set first. Open the module in the IDE, pop up the module’s options menu by clicking the black triangle in the upper-right corner of the window, and make sure “Run as __main__” is checked. This setting is saved with the module, so you only have to do this once per module.

On UNIX-compatible systems (including Mac OS X), you can run a module from the command line: `python `odbchelper.py``

### Example 1.2. Output of `odbchelper.py`

    server=mpilgrim;uid=sa;database=master;pwd=secret