Updated internal design document

esp_modem/docs/internal_desing.md

@@ -2,7 +2,7 @@
 
 ## Design decisions
 
-* Use C++ (lambdas, templates) with additional C API
+* Use C++ with additional C API
   
   | esp-modem in C | esp-modem in C++ |
   |----------------|---------------|
@@ -11,7 +11,8 @@
     -3908
 ```
 
-* Use exceptions (implement nothrow? possibly using `assert()`)
+* Use exceptions
+  - Use macro wrapper over `try-catch` blocks when exceptions off (use `abort()` if `THROW()`) 
 
 | exceptions off | exceptions on |
 |----------------|---------------|
@@ -40,21 +41,11 @@ Total image size:~ 879812 bytes (.bin may be padded larger)                    8
 ```
 * Initializes and allocates in the constructor (might throw)
   - easier code with exceptions ON, with exceptions OFF alloc/init failures are not treated as runtime error (program aborts)
-* Implements different devices with template specialization
-  - Specific device abstraction overrides methods, but does not use virtual function dispatch (modeled as `DCE<SpecificModule>`)
-  - Use cases: Implement a minimal device (ModuleIf), add new AT commands (oOnly in compile time).
-  - Possibly use Module with DTE only (no DCE, no Netif) for sending AT commands without network
+  - break down long initialization in constructor into more private methods
+* Implements different devices using inheritance from `GenericModule`, which is the most general implementation of a common modem
+  - Internally uses templates with device specialization (modeled as `DCE<SpecificModule>`) which could be used as well for some special cases, 
+  such as implantation of a minimal device (ModuleIf), add new AT commands (oOnly in compile time), or using the Module with DTE only (no DCE, no Netif) for sending AT commands without network
   
-Example:
-```
-class SIM7600: public GenericModule {
-    using GenericModule::GenericModule;
-public:
-    command_result get_module_name(std::string& name); // overrides, but is no virtual
-};
-```
-method `get_module_name()` reimplements the *same* method in `GenericModule`
-
 ## DCE collaboration model
 
 The diagram describes how the DCE class collaborates with DTE, PPP and the device abstraction