session

`session` is a built-in global object for inspecting and managing Expr sessions.

It is used directly by name. Do not call `session()`.

A session stores root variables, user-defined functions, user-defined classes, and the last result for a named evaluation context.

`session` is a predefined global object. It is not created with a constructor.

print(session.current);

Properties are read-only. Use session methods to change session state.

print(session.current);

`clone()` is not supported for `session`.

Returns session names separated by new lines.

print(session.list());

Returns variables in the current session, one per line.

Each line contains the variable name and value text.

print(session.list_variables());

Returns built-in function names, one per line.

print(session.list_functions_builtin());

Returns built-in object constructor names, one per line.

print(session.list_classes_builtin());

Returns user-defined function names in the current session, one per line.

print(session.list_functions());

Returns user-defined class names in the current session, one per line.

print(session.list_classes());

Creates a new session named `name`.

`create()` does not switch the current context. Use `join(name)` to start using the new session.

If the session already exists, an error result is returned.

session.create('job1');
print(session.current);      // unchanged
 
session.join('job1');
print(session.current);      // job1

Deletes the session named `name`.

`delete()` does not switch the current context. Deleting the active session returns an error result. The fallback empty-name session cannot be deleted.

Join another session, or join the fallback session with session.join(''), before deleting a session that was active.

old = session.current;
job = 'old_job';
 
session.create(job);
session.set_variable(job, 'old_session', old);
session.join(job);
 
// use job session here
 
session.join(old_session);
session.delete(job);

Switches the current context to an existing session.

If the session does not exist, an error is raised. Passing an empty string joins the fallback empty-name session.

session.join('job1');
 
session.join('');            // fallback empty-name session

Clears variables, user-defined functions, and user-defined classes from the current session.

Built-in global objects are restored after the clear operation.

session.clear();

Returns `true` if `sessionName` contains `variableName`.

Use an empty `sessionName` to check the fallback session. If the named session does not exist, an error is raised.

exists = session.has_variable('job1', 'part_count');

Returns a variable from another session.

Use an empty `sessionName` to read from the fallback session. If the session or variable does not exist, an error is raised.

Object values must be cloneable. Non-cloneable object values cannot be copied between sessions.

count = session.get_variable('job1', 'part_count');

Sets a root variable in another session.

Use an empty `sessionName` to write to the fallback session. Passing `none()` removes the variable.

Object values must be cloneable. Non-cloneable object values cannot be copied between sessions.

Protected built-in global names such as `state`, `settings`, `gcode`, `controller`, `session`, and `python` cannot be overwritten.

old = session.current;
job = 'probe_job_001';
 
session.create(job);
session.set_variable(job, 'old_session', old);
session.join(job);
 
result = 17;
 
session.set_variable(old_session, 'result', result);
session.join(old_session);
session.delete(job);

`session` is a protected built-in global name. The name itself cannot be overwritten.

session = 1;      // error

Use `session` methods to create, join, delete, clear, and inspect sessions.

old = session.current;
job = 'probe_job_001';
 
session.create(job);
session.set_variable(job, 'old_session', old);
session.join(job);
 
safe_z = 5;
feed = 100;
result = safe_z + feed;
 
session.set_variable(old_session, 'probe_result', result);
session.join(old_session);
session.delete(job);
 
print(probe_result);

Previous: controller

Next: python