The document discusses WTF oriented programming techniques including: - Using try/catch blocks to safely access nested object attributes - Applying the Law of Demeter to avoid violating encapsulation - Mapping and selecting arrays instead of iterating with each - Storing translations in locale files instead of hardcoding strings - Conditional logic to dynamically set form field values The examples provide concise code snippets that implement various WTF patterns for handling errors, following principles of object-oriented design, and internationalization.

1. WTF ORIENTED PROGRAMMING
by @AkitaOnRails

6. $('a').click(function(){
window.location
=
$(a).attr('href');
})

7. project_id
=
@user.project
==
nil
?
nil
:
@user.project.id

8. project_id
=
@user.project
==
nil
?
nil
:
@user.project.id
project_id
=
@user.try(:project).try(:id)

9. @politician
=
Politician.where(name:
"Terminator").first
puts
@politician.try(:studio).try(:name)

10. @politician
=
Politician.where(name:
"Terminator").first
puts
@politician.try(:studio).try(:name)
LAW OF DEMETER

11. @politician
=
Politician.where(name:
"Terminator").first
puts
@politician.try(:studio).try(:name)
LAW OF DEMETER

12. class
Politician
delegate
:name,
to:
:studio,
prefix:
true,
allow_nil:
true
#
...
end
@politician.studio.name

13. class
Politician
delegate
:name,
to:
:studio,
prefix:
true,
allow_nil:
true
#
...
end
@politician.studio.name@politician.studio_name

14. class
Politician
delegate
:name,
to:
:studio,
prefix:
true,
allow_nil:
true
#
...
end
@politician.studio.name@politician.studio_name

16. array
=
[]
list.each
do
|state|
array
<<
[state.name,
state.acronym]
end
array

17. array
=
[]
list.each
do
|state|
array
<<
[state.name,
state.acronym]
end
array
for
state
in
list

18. array
=
[]
list.each
do
|state|
array
<<
[state.name,
state.acronym]
end
array
list.map
{
|state|
[state.name,
state.acronym]
}
for
state
in
list

19. array
=
[]
list.each
do
|state|
if
state.name
=~
/^S/
array
<<
[state.name,
state.acronym]
end
end
array

20. array
=
[]
list.each
do
|state|
if
state.name
=~
/^S/
array
<<
[state.name,
state.acronym]
end
end
array
list.
select
{
|state|
state.name
=~
/^S/
}.
map
{
|state|
[state.name,
state.acronym]
}

21. def
formatdate(d)
months
=
Hash.new
months["Jan"]
=
"janeiro"
months["Feb"]
=
"fevereiro"
#
...
months["Dec"]
=
"dezembro"
weeks
=
Hash.new
weeks["Sun"]
=
"Domingo"
#
...
weeks["Fri"]
=
"Sexta"
weeks["Sat"]
=
"Sábado"
return
weeks[d.strftime("%a")]+",
"+d.strftime("%d")+"
de
"+months[d.strftime("%b")]
end

22. def
formatdate(d)
months
=
Hash.new
months["Jan"]
=
"janeiro"
months["Feb"]
=
"fevereiro"
#
...
months["Dec"]
=
"dezembro"
weeks
=
Hash.new
weeks["Sun"]
=
"Domingo"
#
...
weeks["Fri"]
=
"Sexta"
weeks["Sat"]
=
"Sábado"
return
weeks[d.strftime("%a")]+",
"+d.strftime("%d")+"
de
"+months[d.strftime("%b")]
end
#
config/locales/pt-­‐BR.yml
pt-­‐BR:
time:
formats:
short_wday:
"%a,
%d
de
%B”
d.to_s(:short_wday)

23. .row
.wrap-­‐select
select.payment-­‐select
-­‐
if
@payment_type
==
'pagamento'
option.icons-­‐select.card-­‐credit[value="pagamento"
data-­‐foo="card-­‐credit"
selected]
Pagamento
-­‐
else
option.icons-­‐select.card-­‐credit
value="pagamento"
data-­‐foo="card-­‐credit"
Pagamento
-­‐
if
@payment_type.include?
'cartao'
option.icons-­‐select.card-­‐credit[value="cartao"
data-­‐foo="card-­‐credit"
selected]
Cartão
-­‐
else
option.icons-­‐select.card-­‐credit
value="cartao"
data-­‐foo="card-­‐credit"
Cartão
-­‐
if
@payment_type
==
'dinheiro'
option.icons-­‐select.cash[value="dinheiro"
data-­‐foo="cash"
selected]
Dinheiro
-­‐
else
option.icons-­‐select.cash
value="dinheiro"
data-­‐foo="cash"
Dinheiro
-­‐
if
@payment_type
==
'boleto'
option.icons-­‐select.banking-­‐billet[value="boleto"
data-­‐foo="banking-­‐billet"
selected]
Boleto
-­‐
else
option.icons-­‐select.banking-­‐billet
value="boleto"
data-­‐foo="banking-­‐billet"
Boleto

24. .row
.wrap-­‐select
select.payment-­‐select
-­‐
if
@payment_type
==
'pagamento'
option.icons-­‐select.card-­‐credit[value="pagamento"
data-­‐foo="card-­‐credit"
selected]
Pagamento
-­‐
else
option.icons-­‐select.card-­‐credit
value="pagamento"
data-­‐foo="card-­‐credit"
Pagamento
-­‐
if
@payment_type.include?
'cartao'
option.icons-­‐select.card-­‐credit[value="cartao"
data-­‐foo="card-­‐credit"
selected]
Cartão
-­‐
else
option.icons-­‐select.card-­‐credit
value="cartao"
data-­‐foo="card-­‐credit"
Cartão
-­‐
if
@payment_type
==
'dinheiro'
option.icons-­‐select.cash[value="dinheiro"
data-­‐foo="cash"
selected]
Dinheiro
-­‐
else
option.icons-­‐select.cash
value="dinheiro"
data-­‐foo="cash"
Dinheiro
-­‐
if
@payment_type
==
'boleto'
option.icons-­‐select.banking-­‐billet[value="boleto"
data-­‐foo="banking-­‐billet"
selected]
Boleto
-­‐
else
option.icons-­‐select.banking-­‐billet
value="boleto"
data-­‐foo="banking-­‐billet"
Boleto
.row
.wrap-­‐select
select.payment-­‐select
-­‐
pc
=
%w(card-­‐credit
card-­‐credit
cash
banking-­‐billet)
-­‐
%w(pagamento
cartao
dinheiro
boleto).each_with_index
do
|i,
ptype|
option.icons-­‐select[class=pc[i]
value=ptype
data-­‐foo=pc[i]
selected=(@payment_type==ptype)]
I18n.t(ptype)

25. <?php
if
(LANGUAGE
==
'en')
{
?>
<body
class="en">
<?php
}
?>
<?php
if
(LANGUAGE
==
'pt')
{
?>
<body
class="pt">
<?php
}
?>
<?php
if
(LANGUAGE
==
'mx')
{
?>
<body
class="mx">
<?php
}
?>
<?php
if
(LANGUAGE
==
'kp')
{
?>
<body
class="kp">
<?php
}
?>

26. <?php
if
(LANGUAGE
==
'en')
{
?>
<body
class="en">
<?php
}
?>
<?php
if
(LANGUAGE
==
'pt')
{
?>
<body
class="pt">
<?php
}
?>
<?php
if
(LANGUAGE
==
'mx')
{
?>
<body
class="mx">
<?php
}
?>
<?php
if
(LANGUAGE
==
'kp')
{
?>
<body
class="kp">
<?php
}
?>
<body
class="<?php
LANGUAGE
?>">

27. address
=
((!client.street.to_s.nil?)?
client.street.to_s
:
"")
+
((!client.number.to_s.nil?)?
"
Nº
"
+
client.number.to_s
:
"")
+
"
"
+
((!client.city.to_s.nil?)?
client.city.to_s
:
"")
+
((!client.zip.to_s.nil?)?
"
-­‐
CEP:
"
+
client.zip.to_s
:
"")

28. address
=
((!client.street.to_s.nil?)?
client.street.to_s
:
"")
+
((!client.number.to_s.nil?)?
"
Nº
"
+
client.number.to_s
:
"")
+
"
"
+
((!client.city.to_s.nil?)?
client.city.to_s
:
"")
+
((!client.zip.to_s.nil?)?
"
-­‐
CEP:
"
+
client.zip.to_s
:
"")
address
=
"#{client.street}
Nº
#{client.number}
#{client.city}
-­‐
CEP:
#{client.zip}"

29. address
=
((!client.street.to_s.nil?)?
client.street.to_s
:
"")
+
((!client.number.to_s.nil?)?
"
Nº
"
+
client.number.to_s
:
"")
+
"
"
+
((!client.city.to_s.nil?)?
client.city.to_s
:
"")
+
((!client.zip.to_s.nil?)?
"
-­‐
CEP:
"
+
client.zip.to_s
:
"")
address
=
"#{client.street}
Nº
#{client.number}
#{client.city}
-­‐
CEP:
#{client.zip}"
address
=
"%s
Nº
%s
%s
-­‐
CEP:
%s"
%
[client.street,
client.number,
client.city,
client.zip]

30. address
=
((!client.street.to_s.nil?)?
client.street.to_s
:
"")
+
((!client.number.to_s.nil?)?
"
Nº
"
+
client.number.to_s
:
"")
+
"
"
+
((!client.city.to_s.nil?)?
client.city.to_s
:
"")
+
((!client.zip.to_s.nil?)?
"
-­‐
CEP:
"
+
client.zip.to_s
:
"")
address
=
"#{client.street}
Nº
#{client.number}
#{client.city}
-­‐
CEP:
#{client.zip}"
address
=
"%s
Nº
%s
%s
-­‐
CEP:
%s"
%
[client.street,
client.number,
client.city,
client.zip]
class
ClientDecorator
#
...
def
formatted_address
"%s
Nº
%s
%s
-­‐
CEP:
%s"
%
[street,
number,
city,
zip]
end
end

31. –Jamie Zawinksi
“Some people, when confronted with a problem,
think, “I know, I’ll use regular expressions.” Now
they have two problems.”
http://davidcel.is/blog/2012/09/06/stop-validating-email-addresses-with-regex/

32. class
User
<
ActiveRecord::Base
validates
:email,
format:
{
with:
/A[^@]+@([^@.]+.)+[^@.]+z/
}
end

33. class
User
<
ActiveRecord::Base
validates
:email,
format:
{
with:
/A[^@]+@([^@.]+.)+[^@.]+z/
}
end
class
EmailValidator
<
ActiveModel::EachValidator
def
validate_each(record,
attribute,
value)
unless
email_valid?(value)
record.errors[attribute]
<<
(options[:message]
||
"must
be
a
valid
email")
end
end
def
email_valid?(email)
Mail::Address.new(email)
true
rescue
Mail::Field::ParseError
=>
e
false
end
end

34. class
User
<
ActiveRecord::Base
validates
:email,
format:
{
with:
/A[^@]+@([^@.]+.)+[^@.]+z/
}
end
class
EmailValidator
<
ActiveModel::EachValidator
def
validate_each(record,
attribute,
value)
unless
email_valid?(value)
record.errors[attribute]
<<
(options[:message]
||
"must
be
a
valid
email")
end
end
def
email_valid?(email)
Mail::Address.new(email)
true
rescue
Mail::Field::ParseError
=>
e
false
end
end

35. class
User
<
ActiveRecord::Base
validates
:email,
format:
{
with:
/A[^@]+@([^@.]+.)+[^@.]+z/
}
end
class
EmailValidator
<
ActiveModel::EachValidator
def
validate_each(record,
attribute,
value)
unless
email_valid?(value)
record.errors[attribute]
<<
(options[:message]
||
"must
be
a
valid
email")
end
end
def
email_valid?(email)
Mail::Address.new(email)
true
rescue
Mail::Field::ParseError
=>
e
false
end
end
class
User
<
ActiveRecord::Base
validates
:email,
email:
true
end

37. class
User
<
ActiveRecord::Base
validates
:link,
format:
{
with:
/(^$)|(^(http|https)://[a-­‐z0-­‐9]+([-­‐.]{1}[a-­‐z0-­‐9]+)*.[a-­‐z]{2,5}(([0-­‐9]{1,5})?/.*)?$)/ix
}
end
https://coderwall.com/p/ztig5g/validate-urls-in-rails

38. class
User
<
ActiveRecord::Base
validates
:link,
format:
{
with:
/(^$)|(^(http|https)://[a-­‐z0-­‐9]+([-­‐.]{1}[a-­‐z0-­‐9]+)*.[a-­‐z]{2,5}(([0-­‐9]{1,5})?/.*)?$)/ix
}
end
https://coderwall.com/p/ztig5g/validate-urls-in-rails
class
UrlValidator
<
ActiveModel::EachValidator
def
validate_each(record,
attribute,
value)
unless
url_valid?(value)
record.errors[attribute]
<<
(options[:message]
||
"must
be
a
valid
URL")
end
end
#
a
URL
may
be
technically
well-­‐formed
but
may
#
not
actually
be
valid,
so
this
checks
for
both.
def
url_valid?(url)
url
=
URI.parse(url)
rescue
false
url.kind_of?(URI::HTTP)
||
url.kind_of?(URI::HTTPS)
end
end

39. class
User
<
ActiveRecord::Base
validates
:link,
format:
{
with:
/(^$)|(^(http|https)://[a-­‐z0-­‐9]+([-­‐.]{1}[a-­‐z0-­‐9]+)*.[a-­‐z]{2,5}(([0-­‐9]{1,5})?/.*)?$)/ix
}
end
https://coderwall.com/p/ztig5g/validate-urls-in-rails
class
UrlValidator
<
ActiveModel::EachValidator
def
validate_each(record,
attribute,
value)
unless
url_valid?(value)
record.errors[attribute]
<<
(options[:message]
||
"must
be
a
valid
URL")
end
end
#
a
URL
may
be
technically
well-­‐formed
but
may
#
not
actually
be
valid,
so
this
checks
for
both.
def
url_valid?(url)
url
=
URI.parse(url)
rescue
false
url.kind_of?(URI::HTTP)
||
url.kind_of?(URI::HTTPS)
end
end

40. class
User
<
ActiveRecord::Base
validates
:link,
url:
true
end
class
User
<
ActiveRecord::Base
validates
:link,
format:
{
with:
/(^$)|(^(http|https)://[a-­‐z0-­‐9]+([-­‐.]{1}[a-­‐z0-­‐9]+)*.[a-­‐z]{2,5}(([0-­‐9]{1,5})?/.*)?$)/ix
}
end
https://coderwall.com/p/ztig5g/validate-urls-in-rails
class
UrlValidator
<
ActiveModel::EachValidator
def
validate_each(record,
attribute,
value)
unless
url_valid?(value)
record.errors[attribute]
<<
(options[:message]
||
"must
be
a
valid
URL")
end
end
#
a
URL
may
be
technically
well-­‐formed
but
may
#
not
actually
be
valid,
so
this
checks
for
both.
def
url_valid?(url)
url
=
URI.parse(url)
rescue
false
url.kind_of?(URI::HTTP)
||
url.kind_of?(URI::HTTPS)
end
end

41. def
query
Vote.connection.select_values
<<-­‐SQL
SELECT
voteable_id
FROM
votes
LEFT
OUTER
JOIN
authorships
ON
authorships.bill_id
=
voteable_id
LEFT
OUTER
JOIN
politicians
ON
politicians.id
=
politician_id
WHERE
voteable_type
=
'Bill'
AND
person_type
=
'User'
AND
votes.created_at
>=
now()
-­‐
interval
'90
days'
#{@condition.present??
"AND
#{@condition}"
:
""}
GROUP
BY
voteable_id
ORDER
BY
count(*)
DESC
LIMIT
6;
SQL
end
http://guides.rubyonrails.org/active_record_querying.html

42. def
query
Vote.connection.select_values
<<-­‐SQL
SELECT
voteable_id
FROM
votes
LEFT
OUTER
JOIN
authorships
ON
authorships.bill_id
=
voteable_id
LEFT
OUTER
JOIN
politicians
ON
politicians.id
=
politician_id
WHERE
voteable_type
=
'Bill'
AND
person_type
=
'User'
AND
votes.created_at
>=
now()
-­‐
interval
'90
days'
#{@condition.present??
"AND
#{@condition}"
:
""}
GROUP
BY
voteable_id
ORDER
BY
count(*)
DESC
LIMIT
6;
SQL
end
def
query
query
=
Vote.select('voteable_id')
joins("LEFT
OUTER
JOIN
authorships
ON
authorships.bill_id
=
voteable_id").
joins("LEFT
OUTER
JOIN
politicians
ON
politicians.id
=
politician_id").
where(voteable_type:
'Bill',
person_type:
'User').
where("votes.created_at
>=
now()
-­‐
interval
'90
days'").
group('voteable_id').
order('count(*)
desc').
limit(6)
query
=
query.where(@condition)
if
@condition.present?
query
end
http://guides.rubyonrails.org/active_record_querying.html

58. OBRIGADO!
@akitaonrails