# Your own if/else

**URL:** <https://www.ruby-forum.com/t/your-own-if-else/128578>\
**Category:** Ruby\
**Created:** [February 9, 2008, 12:05am UTC](https://www.ruby-forum.com/t/your-own-if-else/128578 "2008-02-09T00:05:44Z")\
**Posts on this page:** 6\
**Page:** 1

<div class="post-metadata">

**Author:** ![marcin\_r](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/e5b9ba/32.png) [@marcin\_r](https://www.ruby-forum.com/u/marcin_r)\
**Post date:** [February 9, 2008, 12:05am UTC](https://www.ruby-forum.com/t/your-own-if-else/128578/1 "2008-02-09T00:05:44Z")

</div>

Hello i remeber someone asking fif it’s possible in Ruby - and i have no  
idea if it was replyied, anyway i wanted to share my idea how to make  
your own if/else/elsif 🙂

class Object  
def else  
self  
end

def elsif(condition,&block)  
self  
end

def if(condition,&block)  
(!condition && Else) || (condition && block.call)  
end  
end

class Else  
def self.else(&block)  
block.call  
end

def self.elsif(condition, &block)  
self.if(condition, &block)  
end  
end

and now we can do:

irb(main):024:0\> self.if(true){:true}.else{:false}  
=\> :true  
irb(main):025:0\> self.if(false){:true}.else{:false}  
=\> :false  
irb(main):051:0\> self.if(false){:true}.elsif(true){:true}.else{nil}  
=\> :true  
irb(main):052:0\> self.if(false){:true}.elsif(false){:true}.else{nil}  
=\> nil  
irb(main):053:0\> self.if(true){:ok}.elsif(true){:not\_ok}.else{:not\_ok}  
=\> :ok  
irb(main):056:0\> self.if(false){:not\_ok}.elsif(true){:ok}.else{:not\_ok}  
=\> :ok

this aproach is elegant becouse even if object have method else or elif  
or even if declared then it’ll bahave as expected !!!  
Also i didn’t use any of old if/else statements, i didn’t even use tri  
argument operator (cond ? true : false), it’s all implemented using  
boolean logic!!

Ok, now probably comes question - what we can do with it - of course -  
create less boolean logic!!!

module Fuzzy  
def self.if(float, &block)  
condition = rand \<= float  
(!condition && Else) || (condition && block.call)  
end  
end

now we provide if function with float between 0 and 1 - which represents  
probability of achieveing goal

Fuzzy.if(0.99){puts “pretty standard stuff”}.else{puts “fuck man, you  
really have luck”}

with some luck (3th try for me) you can get something like this:  
irb(main):097:0\> 10.times{ Fuzzy.if(0.99){puts “pretty standard  
stuff”}.else{puts “fuck man, you really have luck”} }  
pretty standard stuff  
pretty standard stuff  
pretty standard stuff  
pretty standard stuff  
fuck man, you really have luck  
pretty standard stuff  
pretty standard stuff  
pretty standard stuff  
pretty standard stuff  
pretty standard stuff  
=\> 10

What else - of course this way you can do random mutations in genetic  
algorithms, of course there’s other ways to achieve that - but this one  
is fun 😃

currently there’s only one problem with this:

irb(main):099:0\> self.if(false){:not\_ok}  
=\> Else  
while normally you get nil, also Else evaluates to \>true\< in  
expressions, i thought about using Nil or False class instead of else -  
but then block returning nil or false would trigger else block too.  
so there’s tradeoff. Also Else class could cause name conficts so  
someone can rename it to  
WierdClassThatServesOnlyAsMetaProgramingMagickElse to avoid it 🙂

* * *

And last thing - i tried hacking ruby interpreter to treat \>if\< not as  
keyword - but as Kernel method - but not much luck yet,

have phun with Ruby 🙂

---

<div class="post-metadata">

**Author:** ![marcin\_r](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/e5b9ba/32.png) [@marcin\_r](https://www.ruby-forum.com/u/marcin_r)\
**Post date:** [February 9, 2008, 4:10am UTC](https://www.ruby-forum.com/t/your-own-if-else/128578/2 "2008-02-09T04:10:14Z")

</div>

On Feb 8, 6:03 pm, Marcin R. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote:

> ```
> self
> 
> ```
> 
> end  
> irb(main):025:0\> self.if(false){:true}.else{:false}  
> this aproach is elegant becouse even if object have method else or elif  
> condition = rand \<= float  
> with some luck (3th try for me) you can get something like this:  
> pretty standard stuff  
> =\> Else  
> I bet you could fix that with lazy evaluation.

T.

---

<div class="post-metadata">

**Author:** ![marcin\_r](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/e5b9ba/32.png) [@marcin\_r](https://www.ruby-forum.com/u/marcin_r)\
**Post date:** [February 9, 2008, 4:21am UTC](https://www.ruby-forum.com/t/your-own-if-else/128578/3 "2008-02-09T04:21:58Z")

</div>

> I bet you could fix that with lazy evaluation.
> 
> T.

Fix what? and how exactly? 🙂

---

<div class="post-metadata">

**Author:** ![marcin\_r](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/e5b9ba/32.png) [@marcin\_r](https://www.ruby-forum.com/u/marcin_r)\
**Post date:** [February 9, 2008, 2:20pm UTC](https://www.ruby-forum.com/t/your-own-if-else/128578/4 "2008-02-09T14:20:59Z")

</div>

Curt S. wrote:

> Actually, I find the Smalltalk way a little more elegant. The booleans  
> have true:, false:, and true:false: methods; each of the parameters  
> takes a block:
> 
> ```
> x > 3 true: [1 + 1] false [0]
> 
> ```
> 
> (If I recall correctly.)
> 
> cjs  
> Well you can do it with ruby (and even c)like this:

x \>3 ? [1+2] : [0]

🙂  
Inyaway i just wanted to make someone’s life little easier, and/or more  
fun 🙂

---

<div class="post-metadata">

**Author:** ![marcin\_r](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/e5b9ba/32.png) [@marcin\_r](https://www.ruby-forum.com/u/marcin_r)\
**Post date:** [February 9, 2008, 2:25pm UTC](https://www.ruby-forum.com/t/your-own-if-else/128578/5 "2008-02-09T14:25:42Z")

</div>

On 2/9/08, Curt S. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote:

> Actually, I find the Smalltalk way a little more elegant. The booleans  
> have true:, false:, and true:false: methods; each of the parameters  
> takes a block:
> 
> ```
> x > 3 true: [1 + 1] false [0]
> 
> ```
> 
> (If I recall correctly.)

```
x > 3 ifTrue:[1 + 1] ifFalse:[0]

```

However, most Smalltalk implementations cheat and the compiler turns  
this into test and branch bytecodes rather than sending the  
ifTrue:ifFalse: message

–  
Rick DeNatale

My blog on Ruby  
[http://talklikeaduck.denhaven2.com/](http://talklikeaduck.denhaven2.com/)

---

<div class="post-metadata">

**Author:** ![marcin\_r](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/e5b9ba/32.png) [@marcin\_r](https://www.ruby-forum.com/u/marcin_r)\
**Post date:** [February 9, 2008, 7:34am UTC](https://www.ruby-forum.com/t/your-own-if-else/128578/6 "2008-02-09T07:34:41Z")

</div>

Actually, I find the Smalltalk way a little more elegant. The booleans  
have true:, false:, and true:false: methods; each of the parameters  
takes a block:

```
x > 3 true: [1 + 1] false [0]

```

(If I recall correctly.)

cjs