Refactor Introduce With

Code with many references attributes or methods of another object can be simplifed by introducing a "With ... End With" block. This can be particularly effective if a complex expression is repeated with every reference.

Languages:

• VbClassic
• PascalLanguage

Alternatives:

• Consider IntroduceLocalVariable? to evaluate a complex expression in only one place.
• FeatureEnvy: Consider ExtractMethod and MoveMethod to put the code in the object where the attributes lie. IntroduceForeignMethod? if the target object can't be changed.

Related Refactorings:

• RefactorEliminateWith if it's too sparsely used, or to remedy the FeatureEnvy smell "With" blocks often emit.

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[Examples]

In VbClassic: from...

rsObject.Open ...
If rsObject.RecordCount = 0 Then
  rsObject.AddNew
  rsObject!PK = value
End If
rsObject!Attr = value

to...

With rsObject
  .Open ...
  If .RecordCount = 0 Then
    .AddNew
    !PK = value
  End If
  !Attr = value
End With

PascalLanguage: from...

emp.name       := "Joe";
emp.status     := "X";
emp.bday.month :=    6;
emp.bday.day   :=   27;
emp.bday.year  := 1958;

to...

with emp do
begin
  name   := "Joe";
  status := "X";
  with bday do
  begin
    month :=    6;
    day   :=   27;
    year  := 1958;
  end
end

Applicability to other languages: Applies to any language supporting the "with" shorthand. Examples: Pascal

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The refactoring can be done one step further, by removing the variable completely:

(Example in VbClassic) from...

set rst = dbs.TableDefs("tblWhatEver").OpenRecordset(dbOpenTable)
If not rst.EOF() Then
  rst.AddNew
  rst!PK = value
  rst.Update
  rst.Close
End If
Set rst = Nothing

to...

With dbs.TableDefs("tblWhatEver").OpenRecordset(dbOpenTable)
  If not .EOF() Then
    .AddNew
    !PK = value
    .Update
    .Close
  End If
End With

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ContributorsList: JeffGrigg, (name of Pascal example author missing)

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[CategoryRefactoring/RefactoringLanguage]