IoC interface as parameter

  • Thread starter Thread starter AMP
  • Start date Start date
A

AMP

Hello,
If I pass an interface as a parameter to a constructor, where does the
implementation come from? I'm just reading about this and they are
saying it help seperation of concerns, but not sure how.
From Apress Book:
public class PasswordResetHelper
{
private IEmailSender _emailSender;
private ILogWriter _logWriter;
// Constructor
public PasswordResetHelper(IEmailSender emailSender, ILogWriter
logWriter)
{
// This is the Inversion-of-Control bit. The constructor demands
instances
// of IEmailSender and ILogWriter, which we save and will use later.
this._emailSender = emailSender;
this._logWriter = logWriter;
}
// Rest of code uses _emailSender and _logWriter
}
 
If I pass an interface as a parameter to a constructor, where does the
implementation come from? I'm just reading about this and they are
saying it help seperation of concerns, but not sure how.
From Apress Book:
public class PasswordResetHelper
{
private IEmailSender _emailSender;
private ILogWriter _logWriter;
// Constructor
public PasswordResetHelper(IEmailSender emailSender, ILogWriter
logWriter)
{
// This is the Inversion-of-Control bit. The constructor demands
instances
// of IEmailSender and ILogWriter, which we save and will use later.
this._emailSender = emailSender;
this._logWriter = logWriter;
}
// Rest of code uses _emailSender and _logWriter
}
Click to expand...

Whatever the caller passes that implements that
interface.

It can be hardcoded or it can be based on configuration (the
subject line says IoC so this is a possibility).

Arne
 
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