Installation - Pharo 7

Evaluate this code in a Playground to load the Object Miners model and debugger:

Metacello new
    baseline: 'ObjectMiners';
    repository: 'github://ClotildeToullec/ObjectMiners';
    load.

Authors

Design and implementation:

• Steven Costiou
• Clotilde Toullec

Acknowledgments

• Alain Plantec
• Mickaël Kerboeuf
• Stéphane Ducasse

Icons and logos by Yann Plunian.

Object Miners API

We describe the interface available from Object Miners instances. Through this API developers configure what objects to capture as well as how to capture and interact with those objects. We used this API as a guide for our Pharo implementation (https://github.com/ClotildeToullec/ObjectMiners).

Reaching objects of interest

This interface provide means to reach objects of interest in the control flow of a program. Basically it defines where the object miner receiving the message will install itself.

Object Miners API for reaching objects read or written to instance and temporary variables

Variable API	Parameters
reachInstVar(varName, className, option) Specifies an instance variable to reach in the control flow of the program.	varName: the inst. var. name String className: the name of the class in which varName is defined String option: "read", "write" or "all" String, specifies on which case of variable access reaching the object.
reachTemporaryOrParameter(varName, methodName, className, option) Specifies a temporary variable or parameter to reach in the control flow of the program	varName: the temporary variable or method parameter name String methodName: the name of the method in which varName is defined String. The option is not available for parameters. className: the name of the class in which the method methodName is defined String option: "read", "write" or "all" String
reachFromAST(anASTNode) Configures the miner to reach an anonymous object from a specific source code expression.	anASTNode: the abstract syntax tree node representing the expression from which an object will be returned.

Capturing objects

The following APIs show interfaces to define which objects to capture, to define how to capture those objects, and recording strategies.

Object Miners capture API: defining what objects to capture

Object capture API	Parameters
captureContext(reificationsArray) Specifies which entities to capture from the execution context of the reached object.	reificationsArray: an array of strings, containing the names of contextual entities to be reified and captured
recordIntermediateObjects(boolean) (De)activates the recording of objects produced by sub-computations of an instrumented expression.	boolean: true or false (false as default), specifies if intermediate objects returned by the execution of sub-expressions of an instrumented expression must also be recorded

Available contextual entities at capture time

All objects

object	The object in which the miner is installed.
class	The class of the object in which the miner is installed.
context	The execution context.

Variables

name	The variable name.
oldValue	The previous value of the variable when it is subject to an assignment.
newValue	The value assigned to the variable when it is subject to an assignment.

Anonymous objects

arguments	The arguments of the message creating the captured object.
receiver	The receiver of the message creating the captured object.
selector	The selector of the message creating the captured object.
sender	The sender of the message creating the captured object.

Object Miners capture API: defining how to capture objects

Object capture API	Parameters
setCondition(sourceCode) Condition upon which capture will happen. Elements from the execution context (e.g. object to capture) are accessible in the condition.	sourceCode: user defined condition String.
captureHistory(size, loop)} Configures the history of capture objects for a given miner.	size: sets history size (1 by default). loop: true or false, specifies if the history wraps.
captureStack(size) Specifies the captured stack size.	size: the size of the stack (Integer) to store for each capture, 20 method calls by default, 0 means no stack.
recordStrategy(strategy, recordContext) Configures the record strategy to use when a capture is performed. This interface is only implemented in the debugger as an additional tool.	strategy: record strategy (String) to use when capturing an object. recordContext: true or false, specifies if captured context elements should be recorded as well.

Object recording strategies

Strategy	Effect
strongReference	miners keep strong references to captured objects, and prevent them to be destroyed by the program's memory manager.
deepCopy	captured objects and their state are copied and stored by the object miner. Details of how deep copy is implemented are left to developers.

Accessing and interacting with captured objects

Captured objects and reifications from their execution context, i.e., records, can be accessed and interacted with. There are two ways of interacting with captured objects: capture-time interaction which automatically performs actions at the time an object is captured, and post-capture interaction which are manual or tool interaction performed after the capture.

Object Miners capture-time interaction API

Interaction API	Parameters
setAction(sourceCode) User-defined action to be executed just after the capture. Captured elements (e.g. captured objects) are accessible in the action.	sourceCode: user defined action String
haltAfterCapture(size) Breaks the execution after a given number of captures (opens a debugger).	size: number of captured objects (Integer) before breaking the execution.

Object Miners post-capture interaction API

Interaction API	Parameters
getObject(index) Returns an object from the capture history.	index: index of the object (Integer) in the history of captured objects.
getHistoryEntry(index) Returns an entry from the capture history.	index: index of the entry (Integer) to recover from the history of captured objects.
getHistory(size) Returns entries from the capture history.	size: number of entries (Integer) to recover from the history of captured objects.
replayObject(entry, node) Configures a specific object from an entry in the capture history to be replayed. That object must have been captured for the given node in a previous execution.	entry: entry from the history in which to find the replay object for next executions. node: the AST node for which the captured object (found in the entry) will be set as replay