Question

Is it possible to run a function that is specified by using the magic %paste% function in IPython?

In [1]: %paste%
def add_to_index(index,keyword,url):
    for e in index:
        if e[0] == keyword:
            if url not in e[1]:
                e[1].append(url)
            return
    index.append([keyword,[url]])

## -- End pasted text --
Block assigned to '%'

In [2]: %whos
Variable   Type     Data/Info
-----------------------------
%          SList    ['def add_to_index(index,<...>append([keyword,[url]])']

In [3]: add_to_index
---------------------------------------------------------------------------
NameError                                 Traceback (most recent call last)
<ipython-input-3-e3075a18cb0c> in <module>()
----> 1 add_to_index

NameError: name 'add_to_index' is not defined

In [4]: add_to_index(index, 'test', 'http://test.com')
---------------------------------------------------------------------------
NameError                                 Traceback (most recent call last)
<ipython-input-4-580237464b17> in <module>()
----> 1 add_to_index(index, 'test', 'http://test.com')

NameError: name 'add_to_index' is not defined

In [5]:

Answer 1

The paste magic is %paste (no trailing %):

In [3]: %paste
def add_to_index(index,keyword,url):
    for e in index:
        if e[0] == keyword:
            if url not in e[1]:
                e[1].append(url)
            return
    index.append([keyword,[url]])
## -- End pasted text --

In [4]: add_to_index
Out[4]: <function __main__.add_to_index>

What happens in your case is that you are using the optional argument for %paste:

In [5]: %paste?
Type:       Magic function

...(text omitted)

You can also pass a variable name as an argument, e.g. '%paste foo'.
This assigns the pasted block to variable 'foo' as string, without
dedenting or executing it (preceding >>> and + is still stripped)

When you do that the pasted code does not get executed, it is just assigned to the variable you gave as an argument (% in your case).