support bundling with rollup

[pravi]

I'm trying to bundle handlebars with rollup (as webpack has a long list of dependencies), I get the following error. Can you support bundling with rollup?

$ rollup ./lib/handlebars.js 
'default' is not exported by lib/handlebars/compiler/parser.js (imported by lib/handlebars/compiler/base.js). For help fixing this error see https://github.com/rollup/rollup/wiki/Troubleshooting#name-is-not-exported-by-module
Error: 'default' is not exported by lib/handlebars/compiler/parser.js (imported by lib/handlebars/compiler/base.js). For help fixing this error see https://github.com/rollup/rollup/wiki/Troubleshooting#name-is-not-exported-by-module
    at Module.trace (/usr/lib/nodejs/rollup/src/Module.js:362:30)
    at Module.traceExport (/usr/lib/nodejs/rollup/src/Module.js:388:29)
    at Module.trace (/usr/lib/nodejs/rollup/src/Module.js:360:36)
    at ModuleScope.findDeclaration (/usr/lib/nodejs/rollup/src/ast/scopes/ModuleScope.js:47:22)
    at Scope.findDeclaration (/usr/lib/nodejs/rollup/src/ast/scopes/Scope.js:92:39)
    at Identifier.bind (/usr/lib/nodejs/rollup/src/ast/nodes/Identifier.js:7:29)
    at /usr/lib/nodejs/rollup/src/ast/Node.js:6:34
    at AssignmentExpression.eachChild (/usr/lib/nodejs/rollup/src/ast/Node.js:21:5)
    at AssignmentExpression.bind (/usr/lib/nodejs/rollup/src/ast/Node.js:6:8)
    at AssignmentExpression.bind (/usr/lib/nodejs/rollup/src/ast/nodes/AssignmentExpression.js:29:13)
Type rollup --help for help, or visit https://github.com/rollup/rollup/wiki

[msroberts]

This is also an issue for me: because the compiled templates js file does not export anything, rollup does not modify the global Handlebars variable.

Related: #1254, #955

[nknapp]

Could you try manually changing the last lines of lib/handlebars/compiler/parser.js from

exports.__esModule = true;
exports['default'] = handlebars;

to

export default handlebars;

This change would revert part of commit efddc3 and it does reduce code-coverage in the istanbul report. But this reduction seems to be a reporting issue. Maybe this can be handed differently.

At first, it would be interesting if the change solves your problem.

[nknapp]

This should be resolved with #1315