Cloning and Rebuilding

Using the default dictionary cloner

Sometimes it may be beneficial to have a base IVariableReplacer that can be further customised later on in the execution of your application.

This can be seen as utilising inheritance or even a partial definition of a variable replacer.

In reality an IVariableReplacer is immutable so this is where the CloneAndConfigure extension method of an IVariableReplacer comes into play:

Note

The cloning does a shallow clone of the variables and copies all the other settings across from the original IVariableReplacer. A custom cloning function can be passed in as an extra argument as demonstrated here

var replacer = new VariableReplacerFactory()
    .Build(c => c.AddVariables(new Dictionary<string, object>
    {
        ["FirstName"] = "Al",
        ["LastName"] = "Jones",
        ["FullName"] = "$(FirstName) $(LastName)"
    }));

var result = replacer.ReplaceVariables(
    "Hello $(FullName). Can I call you $(FirstName)?"
);
// result should be "Hello Al Jones. Can I call you Al?"

// We configure the second replacer to allow us to replace existing variables.
// Whilst configuring we can replace variables in the cloned collection.
// After creation it is set back to not allow the addition of duplicate
// variable names.
var replacer2 = replacer.CloneAndConfigure(c => c
    .AddVariable("FirstName", "Other"));

var result2 = replacer2.ReplaceVariables(
    "Hello $(FullName). Can I call you $(FirstName)?"
);
// result2 should be "Hello Other Jones. Can I call you Other?"

var firstName = replacer.Variables["FirstName"];
// firstName should be "Al" as the clone will 
// ensure that the initial replacer is preserved

var firstName2 = replacer2.Variables["FirstName"];
// firstName2 should be "Other"

Using the a custom dictionary cloner

var replacer = new VariableReplacerFactory()
    .Build(c => c.AddVariables(new Dictionary<string, object>
    {
        ["FirstName"] = "Al",
        ["LastName"] = "Jones",
        ["FullName"] = "$(FirstName) $(LastName)"
    }));

var result = replacer.ReplaceVariables(
    "Hello $(FullName). Can I call you $(FirstName)?"
);
// result should be "Hello Al Jones. Can I call you Al?"

// We configure the second replacer to allow us to replace existing variables.
// Whilst configuring we can replace variables in the cloned collection.
// After creation it is set back to not allow the addition of duplicate
// variable names.
var replacer2 = replacer.CloneAndConfigure(c => c
    .AddVariable("FirstName", "Other"),

    // This custom cloner just returns the same dictionary
    // which results in any variable changes being replicated
    // in `replacer` and `replacer2`
    originalDictionary => originalDictionary);

var result2 = replacer2.ReplaceVariables(
    "Hello $(FullName). Can I call you $(FirstName)?"
);
// result2 should be "Hello Other Jones. Can I call you Other?"

var firstName = replacer.Variables["FirstName"];
// firstName should be "Other" as  
// we have shared the dictionary

var firstName2 = replacer2.Variables["FirstName"];
// firstName2 should be "Other"