Variables
Variables can be used throughout Continua and created at certain levels in the hierarchy. Environment variable are there by default and cannot be changed, they're the last variable namespace checked when determining a variable's value. The next level of variables checked at the Application level which is the highest level a user can define a variable. A variable defined in the Application namespace can be used anywhere in Continua. The next level of variables are for projects which are defined on the project wizard page followed by configuration variables which are on the configuration wizard page. The final variable namespace and the one at the top of the hierarchy is the Build Namespace. There are 3 ways to define a build level variable. When a build is triggered (defined when creating the trigger), when manually starting a build that prompts for variables and when setting a variable in a stage using the Set Variable Action. Variables can have a value type of Text, Numeric or Expression. Expression variables can contain references to other variable or objects. Variables can later be referenced using the Variables Syntax (do we have a page for this?).
Objects & Expressions
Expressions in Continua are design time references that are evaluated at run time in order to get the required value. When an input field is able to take in an expression, a drop down list of selectable options will be shown. These options are called Objects and their visibility differs depending on the context in which the expression is trying to be used. For example, when adding a stage condition to a stage option, the user is only able to select a list of Agent options since the Stage runs on an Agent and that's the only scope it has. If a user was to specify a specific Agent to run on then they would need to use an expression to get the Agent hostname to check for. The expression would look like this $Agent.Hostname$