# Bow: how not to shoot yourself an arrow in the knee¶

The only reason to use a bow is either you are lazy, or you noticed I only test these. This is the most tested part of the code yet.

My philosophy in testing is: check the component relying on the maximum of your code gives satisfaction since I should traverse most of the point of failure, and then I add a unittest per bug found.

## Hankyu¶

A dict with addition used here : http://github.com/jul/parseweblog

It instanciate like a dict::
```>>> from archery.bow import Hankyu
>>> a = Hankyu(x=1,y=2,z=2)
```
```>>> a+a
{'y': 4, 'x': 2, 'z': 4}
>>> a+-2
{'y': 0, 'x': -1, 'z': 0}
>>> a+.5
{'y': 2.5, 'x': 1.5, 'z': 2.5}
>>> .5+a
{'y': 2.5, 'x': 1.5, 'z': 2.5}
```

```>>> a = Hankyu(data=[1,2],sample=1)
>>> b = Hankyu(data=[3,4],sample=1)
>>> a+b
{'sample': 2, 'data': [1, 2, 3, 4]}
```
If propagates the addition to the included bow::
```>>> a=Hankyu(a=Hankyu(a=1))
>>> b=Hankyu(a=Hankyu(a=2))
>>> a+b
{'a': {'a': 3}}
>>> a+=1
>>> a
{'a': {'a': 2}}
>>>
```

## Daikyu¶

A dict that loves to do a lot of things : * addition; * substraction; * multiplication; * division (please, please be careful).

### Simple algebrae¶

It instanciates like a dict:
```>>> from archery.bow import Daikyu
>>> b=Daikyu(x=2, z=-1)
>>> a=Daikyu(x=1, y=2.0)
>>> a+b
# OUT: {'y': 2.0, 'x': 3, 'z': -1}
>>> b-a
# OUT: {'y': -2.0, 'x': 1, 'z': -1}
>>> -(a-b)
# OUT: {'y': -2.0, 'x': 1, 'z': -1}
>>> a+1
# OUT: {'y': 3.0, 'x': 2}
>>> -1-a
>>> # OUT: {'y': -3.0, 'x': -2}
>>> a*b
# OUT: {'x': 2}
>>> a/b
# OUT: {'x': 0}
>>> 1.0*a/b
# OUT: {'x': 0.5}
```

### Why div is special?¶

Because div is special and I stick to python 2 behaviour on this one.

http://beauty-of-imagination.blogspot.fr/2012/05/dividing-is-not-as-easy-at-it-seems.html

Don’t flame me yet, I can provide another diver, but my brain is yet kaput.

See by yourself::
```>>> b/2
# OUT: {'x': 0, 'z': 0}
>>> b/2.0
# OUT: {'x': 1.0, 'z': -0.5}
>>> 2/b
# OUT: {'x': 0, 'z': -2}
```
But you can correct this::
```>>> 2.0/(1.0*b)
# OUT: {'x': 1.0, 'z': -2.0}
```

### Mixing scalars and records¶

My prefered part :) ::
```>>> 2*Daikyu(x=1, y="lo",z=)
{'y': 'lolo', 'x': 2, 'z': [2, 2]}
>>> Daikyu(y=1, z=1)*Daikyu(x=1, y="lo",z=)*2
{'y': 'lolo', 'z': [2, 2]}
>>> a=Daikyu(dictception=Daikyu(a=1,b=2), sample = 1, data=[1,2])
>>> b=Daikyu(dictception=Daikyu(c=-1,b=2), sample = 2, data=[-1,-2])
>>> a+b
{'sample': 3, 'dictception': {'a': 1, 'c': -1, 'b': 4}, 'data': [1, 2, -1, -2]}
>>> Daikyu(dictception=1, sample=1)* a*b
{'sample': 2, 'dictception': {'b': 4}}
```