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Rosella Dumper

Overview

Data dumping is a common operation especially during program analysis and debugging. Rosella Dumper provides utilities to serialize data into a human readable format and display that data to the user for quick visualization and analysis of complex nested data structures.

Rosella Dumper is intended to be a debugging tool, and is not intended to be a general purpose data-serialization library. It might be possible to use it as such given enough effort and overriding existing behaviors, but a specialized library for the purpose might be a better option.

Concepts

Namespaces

Rosella.Dumper

The Rosella.Dumper namespace provides a function default_dumper() which returns a pre-configured default global Dumper instance.

var d = Rosella.Dumper.default_dumper();

If you want to override the global default with your own instance, you can do this:

var d = < create your dumper here >
Rosella.Dumper.set_default_dumper(d);

Classes

Rosella.Dumper

Rosella.Dumper is the main driver class for the dumper library and the primary user interface. The Dumper holds several different DumpHandler objects, each of which is responsible for dumping certain objects. The Dumper organizes DumpHandlers into three groups: role-based handlers, type-based handlers, and miscellaneous handlers. In addition, there is a fallback handler which is used to dump any object which has not already been handled by the previous collection and a Null handler which handles the special case of Null values.

The general algorithm for dumping looks like this:

  1. If the data is Null, use the Null Handler
  2. Search the type handlers to find one that matches the specific type of the data. If found, use that.
  3. Search the role handlers to find the first one that matches a role implemented by the data object. Use the first one found, if any.
  4. Search all the miscellaneous handlers for any that can handle the data object. Use the first one found, if any.
  5. Use the fallback handler

The user can add or remove handlers in each group to create custom behavior.

The .dump() method is the primary interface of the dumper. It creates and returns a string containing the textual representation of the data. It does not automatically print the data to the console or any file handle.

Rosella.Dumper.DumpHandler

The Rosella.Dumper.DumpHandler is the default handler type and provides basic logic for dumping a string representation of the object. This type is the default fallback dumper, and also serves as the parent type for all other DumpHandlers.

Rosella.Dumper.DumpHandler.Array

The Rosella.Dumper.Dumphandler.Array handler is used to dump any objects which implement the "array" role. It prints a list of items from the array surrounded by square brackets.

Rosella.Dumper.DumpHandler.Hash

The Rosella.Dumper.Dumphandler.Hash handler is used to dump any objects which implement the "hash" role. It prints each key/value pair, surrounded by curly brackets.

Rosella.Dumper.DumpHandler.InspectAttrs

Rosella.Dumper.Dumphandler.InspectAttrs is a miscellaneous handler which can be used to dump the attributes of a user object.

Rosella.Dumper.DumpHandler.Null

The Rosella.Dumper.Dumphandler.Null handler is the default handler for null values. It prints the string "NULL".

Rosella.Dumper.DumpHandler.Object

The Rosella.Dumper.Dumphandler.Object handler is a miscellaneous handler for dumping user-defined objects. It prints a string representation of the object (if any) and the values of the object's attributes, surrounded by parenthesis.

Rosella.Dumper.Emitter

The Rosella.Dumper.Emitter class is the emitter for the library. It is responsible for building and formatting the text representation, including recursive calls to the Dumper for nested data objects.

Examples

Winxed

var d = Rosella.Dumper.default_dumper();
string s = d.dump(my_obj);
say(s);

NQP-rx

Users

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