# Ara's main gem: validation with error message

**URL:** <https://www.ruby-forum.com/t/aras-main-gem-validation-with-error-message/130649>\
**Category:** Ruby\
**Created:** [March 1, 2008, 5:56am UTC](https://www.ruby-forum.com/t/aras-main-gem-validation-with-error-message/130649 "2008-03-01T05:56:12Z")\
**Posts on this page:** 3\
**Page:** 1

<div class="post-metadata">

**Author:** ![PeSSSSaS\_Botp](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/p/ecd19e/32.png) [@PeSSSSaS\_Botp](https://www.ruby-forum.com/u/PeSSSSaS_Botp)\
**Post date:** [March 1, 2008, 5:56am UTC](https://www.ruby-forum.com/t/aras-main-gem-validation-with-error-message/130649/1 "2008-03-01T05:56:12Z")

</div>

Hi,

This request should probably be addressed directly to Ara but maybe  
others may have other ideas, so

Using Ara’s main, I have something like the following,

Main do  
argument :user do  
required  
description “name or userid”  
validate{|user| check1(user)}  
validate{|user| check2(user,child)}  
validate{|user| check3(user,parent)}  
end

def run  
p params[:user].value  
end  
end

Currently, i only get one validation message like,

```
invalid: argument(user)="botp"

```

It would be nice if i could specify/add an (optional) error message for  
each validation, like eg

```
validate("user does not exist"){|user| check1(user)}
validate("user must have child"){|user| check2(user,child)}
validate("user need parent"){|user| check3(user,parent)}

```

Are you there, Ara? 😉

Sorry for your time, Ara, as i’m fond of your main gem.  
Thank you for main.

kind regards -botp

---

<div class="post-metadata">

**Author:** ![PeSSSSaS\_Botp](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/p/ecd19e/32.png) [@PeSSSSaS\_Botp](https://www.ruby-forum.com/u/PeSSSSaS_Botp)\
**Post date:** [March 1, 2008, 5:47pm UTC](https://www.ruby-forum.com/t/aras-main-gem-validation-with-error-message/130649/2 "2008-03-01T17:47:58Z")

</div>

On Fri, Feb 29, 2008 at 9:53 PM, Peña, Botp [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid)  
wrote:

> ```
> validate{|user| check1(user)}
> 
> ```
> 
> Currently, i only get one validation message like,
> 
> Are you there, Ara? 😉
> 
> Sorry for your time, Ara, as i’m fond of your main gem.  
> Thank you for main.
> 
> kind regards -botp

one idea:

cfp2:~ \> cat a.rb  
require ‘main’

Main do  
argument(:user) do  
required  
description ‘name or userid’

```
message = 'YOU CAN USE A CLOSURE'

validate do |user|
  if user == 'foo'
    message = 'message one'
    return false
  end

  if user == 'bar'
    message = 'message two'
    return false
  end

  true
end

error{ STDERR.puts message }

```

end

def run  
p param[:user].value  
end  
end

cfp2:~ \> ruby a.rb foo  
message one

cfp2:~ \> ruby a.rb bar  
message two

cfp2:~ \> ruby a.rb foobar  
“foobar”

---

<div class="post-metadata">

**Author:** ![PeSSSSaS\_Botp](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/p/ecd19e/32.png) [@PeSSSSaS\_Botp](https://www.ruby-forum.com/u/PeSSSSaS_Botp)\
**Post date:** [March 3, 2008, 5:52am UTC](https://www.ruby-forum.com/t/aras-main-gem-validation-with-error-message/130649/3 "2008-03-03T05:52:52Z")

</div>

From: ara.t.howard [[mailto:removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid)]

# message = ‘YOU CAN USE A CLOSURE’

# validate do |user|

# if user == ‘foo’

# message = ‘message one’

# return false

would it be possible to merge those last two lines? maybe something like  
raise\_error ‘message one’ which then flags an error and sends the  
‘message one’ to error(). see below question

# end

# if user == ‘bar’

# message = ‘message two’

# return false

# end

# 

# true

# end

# 

# error{ STDERR.puts message }

standard format of error is error{|msg| …}, how do i set an error  
message so that error can capture it and i can just generically call  
error{|msg| p msg}. no var declaration/tracking needed ie

kind regards -botp