---
title: clsLogCommon
summary: API reference for clsLogCommon.
status: draft
owner: <owner>
last_reviewed: 2026-07-23
library: SAIF.Framework.Logging
reference_type: package
---

# clsLogCommon

`clsLogCommon` is a `Public` shared helper class that centralizes format-string constants and web/non-web context detection used by `clsLogAudit`, `clsLogError`, and `clsLogTrace`. The class itself is public, but its helper methods and properties are `Friend`-scoped (assembly-internal); only its `Public Const` members are part of the external public surface.

## Purpose
- Expose shared `Public Const` format strings used to render error, state, and log-file-name text consistently across the logging entry points.
- Provide `Friend`-scoped web/non-web context detection (`IsWeb`), environment/application-name derivation, calling-method reflection, and log-file naming, used internally by `clsLogAudit`/`clsLogError`/`clsLogTrace`.

## Context
- Namespace: `SAIF.Framework.Logging`
- Assembly/package: `SAIF.BOF.Framework.Logging` (`SAIF.Framework.Logging/SAIF.BOF.Framework.Logging.vbproj`)
- The class declaration is `Public Class clsLogCommon`; its constants are public, while its Shared properties/methods are `Friend`-scoped.

## Public members
| Member | Signature | Purpose |
| --- | --- | --- |
| `ERRORTOSTRINGFORMAT` | `Public Const ERRORTOSTRINGFORMAT As String = "{0,-20}:  {1}{2}"` | Format string used when rendering an individual error field to text. |
| `EXCEPTIONINFOFORMAT` | `Public Const EXCEPTIONINFOFORMAT As String` | Format string used to render exception message/source/stack-trace detail (used by `ErrorInfoStruct`). |
| `MSGSUBJECT` | `Public Const MSGSUBJECT As String = "Error in App:  {0}; Machine:  {1}; Environ:  {2}"` | Format string for the subject line of error-notification emails. |
| `STATEFMTSIMPLE` | `Public Const STATEFMTSIMPLE As String = "{0,-20}=  {1}" & vbCrLf` | Format string for a simple name/value state line (used by `ErrorInfoStruct.ToString`/`ToHTMLString`). |
| `STATEFMTCOMPLEX` | `Public Const STATEFMTCOMPLEX As String = "{0,-20}({1})=  {2}" & vbCrLf` | Format string for a name/type/value state line, used by `GetStateInfo` when rendering non-primitive caller-supplied objects. |
| `TOFILEFORMAT` | `Public Const TOFILEFORMAT As String = "{0}\{1}_{2}_{3:MM}_{4:yyyy}.log"` | Format string used to build a local log file name/path. |

## Behavioral notes
- `IsWeb` (`Friend Shared ReadOnly Property`) returns `True` when `System.Web.HttpContext.Current` is not `Nothing`, and gates whether `ToFile()` on `clsLogAudit`/`clsLogError`/`clsLogTrace` is permitted (see [BR-003](../../business-rules.md#br-003-file-based-logging-is-prohibited-in-web-applications)).
- `GetAppEnvironment`/`GetWebAppName` (both `Friend Shared`) derive an environment/application name by parsing the physical file/module path (splitting on `:` and `\`) rather than reading explicit configuration, an inferred convention rather than a documented contract*.
- `GetCallingMethodInfo` (`Friend Shared`) walks the current stack trace via reflection to find the first frame outside the `Logging` assembly, used to populate trace/context info.
- `GetStateInfo` (`Friend Shared`) renders caller-supplied `ParamArray` objects to text: primitives are rendered via `ToString`, and other objects are rendered property-by-property using `STATEFMTCOMPLEX`.
- `GetToFileName` (`Friend Shared`) builds a temp-directory log file name using `TOFILEFORMAT`, the current process's main module name, and the current date.

## Constraints and usage notes
- Only the six `Public Const` members are usable from outside the `SAIF.BOF.Framework.Logging` assembly; the properties and methods described above are `Friend`-scoped and are internal implementation details shared by `clsLogAudit`, `clsLogError`, and `clsLogTrace`.
- Consumers should not depend on the `Friend`-scoped members remaining stable, since they are not part of the documented external contract.

> **Note:** Statements marked with `*` were inferred from code structure, naming conventions, or
> contextual evidence where direct confirmation was not available in source artifacts. Statements
> marked with `**` could not be confirmed; treat as unknown until verified.

## Sources
- `SAIF.Framework.Logging/clsLogCommon.vb`